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what is an algorithm ? one definition might be a set of steps to accomplish a task . you might have an algorithm for getting from home to school , for making a grilled cheese sandwich , or for finding what you 're looking for in a grocery store . in computer science , an algorithm is a set of steps for a computer prog...
what is an algorithm ? one definition might be a set of steps to accomplish a task .
can an algorithm be termed incorrect ?
what is an algorithm ? one definition might be a set of steps to accomplish a task . you might have an algorithm for getting from home to school , for making a grilled cheese sandwich , or for finding what you 're looking for in a grocery store . in computer science , an algorithm is a set of steps for a computer prog...
what is an algorithm ? one definition might be a set of steps to accomplish a task .
is an algorithm like a routine ?
what is an algorithm ? one definition might be a set of steps to accomplish a task . you might have an algorithm for getting from home to school , for making a grilled cheese sandwich , or for finding what you 're looking for in a grocery store . in computer science , an algorithm is a set of steps for a computer prog...
how do you measure the efficiency of an algorithm ? we could time how long it takes to run the code , but that would only tell us about that particular implementation in a certain programming language on a particular computer and just for the input it was given . instead , computer scientists use a technique called asy...
what is the difference between container and panel in java programming ?
what is an algorithm ? one definition might be a set of steps to accomplish a task . you might have an algorithm for getting from home to school , for making a grilled cheese sandwich , or for finding what you 're looking for in a grocery store . in computer science , an algorithm is a set of steps for a computer prog...
what is an algorithm ? one definition might be a set of steps to accomplish a task .
how long does it usually take until a person knows how to write complex algorithm ?
what is an algorithm ? one definition might be a set of steps to accomplish a task . you might have an algorithm for getting from home to school , for making a grilled cheese sandwich , or for finding what you 're looking for in a grocery store . in computer science , an algorithm is a set of steps for a computer prog...
instead , computer scientists use a technique called asymptotic analysis , which allows algorithms to be compared independently of a particular programming language or hardware so that we can conclusively say that yes , some algorithms are more efficient than others . now you can learn about algorithms and asymptotic a...
is there a specific area of mathematics ( preferably on khan academy ) that i can go through to help me learn the proper math to fully understand how to reduce an algorithm down to asymptotic notation ?
what is an algorithm ? one definition might be a set of steps to accomplish a task . you might have an algorithm for getting from home to school , for making a grilled cheese sandwich , or for finding what you 're looking for in a grocery store . in computer science , an algorithm is a set of steps for a computer prog...
he built the world 's first origami folding robot . tom and devin will teach you many of the algorithms that you would learn in apcs or cs 101 , like searching algorithms , sorting algorithms , recursive algorithms and my personal favorite , graph algorithms . there will be tons of interactive visualizations , quizzes ...
is there any source to find such fundamental algorithms ?
what is an algorithm ? one definition might be a set of steps to accomplish a task . you might have an algorithm for getting from home to school , for making a grilled cheese sandwich , or for finding what you 're looking for in a grocery store . in computer science , an algorithm is a set of steps for a computer prog...
what is an algorithm ? one definition might be a set of steps to accomplish a task .
how to figure out algorithm to solve a problem in dynamic situation ?
what is an algorithm ? one definition might be a set of steps to accomplish a task . you might have an algorithm for getting from home to school , for making a grilled cheese sandwich , or for finding what you 're looking for in a grocery store . in computer science , an algorithm is a set of steps for a computer prog...
he built the world 's first origami folding robot . tom and devin will teach you many of the algorithms that you would learn in apcs or cs 101 , like searching algorithms , sorting algorithms , recursive algorithms and my personal favorite , graph algorithms . there will be tons of interactive visualizations , quizzes ...
what kind of algorithms are being used on the job of a computer engineer ?
what is an algorithm ? one definition might be a set of steps to accomplish a task . you might have an algorithm for getting from home to school , for making a grilled cheese sandwich , or for finding what you 're looking for in a grocery store . in computer science , an algorithm is a set of steps for a computer prog...
let 's talk about a few famous algorithms . how does google hangouts transmit live video across the internet so quickly ? they use audio and video compression algorithms .
how does the internet gather so much info about someone ?
what is an algorithm ? one definition might be a set of steps to accomplish a task . you might have an algorithm for getting from home to school , for making a grilled cheese sandwich , or for finding what you 're looking for in a grocery store . in computer science , an algorithm is a set of steps for a computer prog...
how does google hangouts transmit live video across the internet so quickly ? they use audio and video compression algorithms . how does google maps figure out how to get from dallas , texas to orlando , florida so that you can get to disney world ?
what sort of algorithms does khan academy use ?
- [ voicover ] prejudice is made up of several different components . the first component that we have is a fundamental underlying thought overgeneralized belief , otherwise known as a cognition . we often refer to these as stereotypes . the second aspect to prejudice is that it carries with it an emotional component ,...
in line with the frustration aggression hypothesis , i want to tell you about another hypothesis . and this is called the hypothesis of relative deprivation . now , what the hypothesis of relative deprivation suggests is that people become very frustrated and you get upsurge in prejudice and discrimination when people ...
would conservatives ' negative reaction to obama 's immigration reform be considered a form of the hypothesis of relative deprivation because we 're all immigrants ?
- [ voicover ] prejudice is made up of several different components . the first component that we have is a fundamental underlying thought overgeneralized belief , otherwise known as a cognition . we often refer to these as stereotypes . the second aspect to prejudice is that it carries with it an emotional component ,...
so as you can see , living standards actually do n't increase with time , actually these tend to drop off , maybe because of some economic problem . we 're left with a difference . and it 's this difference that is the relative deprivation .
i wonder what the difference is between the scapegoating mentioned in the video and the psychoanalytic idea of displacement ?
- [ voicover ] prejudice is made up of several different components . the first component that we have is a fundamental underlying thought overgeneralized belief , otherwise known as a cognition . we often refer to these as stereotypes . the second aspect to prejudice is that it carries with it an emotional component ,...
in line with the frustration aggression hypothesis , i want to tell you about another hypothesis . and this is called the hypothesis of relative deprivation . now , what the hypothesis of relative deprivation suggests is that people become very frustrated and you get upsurge in prejudice and discrimination when people ...
why is there upsurge of prejudice in the hypothesis of relative deprivation ?
stacy wants to find the derivative of f of x equals x squared plus one at the point x equals two . her table below shows the average rate of change of f over the intervals from x to two or from two to x , and these are closed intervals , for x-values that get increasingly closer to two . so they get -- so we 're talki...
stacy wants to find the derivative of f of x equals x squared plus one at the point x equals two . her table below shows the average rate of change of f over the intervals from x to two or from two to x , and these are closed intervals , for x-values that get increasingly closer to two . so they get -- so we 're talki...
why do the order of those intervals change ?
stacy wants to find the derivative of f of x equals x squared plus one at the point x equals two . her table below shows the average rate of change of f over the intervals from x to two or from two to x , and these are closed intervals , for x-values that get increasingly closer to two . so they get -- so we 're talki...
she gets even closer to two and the average rate of change gets even closer to four , and then she goes on the other side of two , you could view it as this is approaching , this is -- this is approaching -- this is x approaching two from the left hand side , and this is x approaching two from the right hand side . whe...
and in the table , why do the interval switch side when going from 1.999 to 2.001 ?
stacy wants to find the derivative of f of x equals x squared plus one at the point x equals two . her table below shows the average rate of change of f over the intervals from x to two or from two to x , and these are closed intervals , for x-values that get increasingly closer to two . so they get -- so we 're talki...
stacy wants to find the derivative of f of x equals x squared plus one at the point x equals two . her table below shows the average rate of change of f over the intervals from x to two or from two to x , and these are closed intervals , for x-values that get increasingly closer to two .
this might be a stupid question , but i have not been able to understand what the relation between d ( x ) and f ' ( x ) is , are they the same ?
stacy wants to find the derivative of f of x equals x squared plus one at the point x equals two . her table below shows the average rate of change of f over the intervals from x to two or from two to x , and these are closed intervals , for x-values that get increasingly closer to two . so they get -- so we 're talki...
you might recognize , this is one of the definitions of a derivative . this is one of the definitions of a derivative . this right over here would be f prime of two , the derivative at x equals two is equal to the limit as x approaches two of all of this business .
how are definitions of derivative and limit same ?
let 's look at our gentleman in the middle . he is lying down and he is dreaming . that raises the question , do our dreams have a meaning ? so if he 's thinking about money , relationships , even weird and wonderful things like monsters chasing him down the road , what does that mean ? where are all these dreams comi...
on one side , freud feels that dreams indeed have a meaning and important to helping us to resolve hidden conflicts and understand unconcious feelings , desires , impulses , and that 's his theory of dreams . on the other hand , we have this activation synthesis hypothesis . that suggest that dreams are simply a part o...
in regards to the `` activation synthesis hypothesis '' dream theory , where do the electrical impulses come from , i would assume that since a person is asleep they are unable to perceive anything so what activity creates the electrical impulses ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well that go out to the arms . but these branches that are going up are the ones i 'm going to focus on .
how does this go with lungs ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
and really , the same thing is going on on the aorta side . so on the aorta side , you 've got little branches coming off of the aorta , of course . and these branches are going to branch again , and again , and again , and again .
why does it appear that the aorta is coming from the right ventricle ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
and these oxygen molecules -- these are oxygen molecules over here -- are going to diffuse down into the tissue and get into our glomus cell . it 's going to look something like that . and if you have a lot of oxygen in the blood , of course , a lot of molecules are going to diffuse in .
why do we draw hearts like that when they dont look like that ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
this is really interesting . our cell is depolarizing . it can depolarize .
at 05 , the causes of the depolarization of the glomus cell are low pressure of oxygen , high pressure of carbon dioxide , and low ph , but is n't chemoreceptor detect chemical/concentration ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
and if the oxygen levels fall really low , let 's say they get dangerously low , where the cell is very unhappy , then you 're going to get much more neurotransmitter getting dumped out , and you 're going to get many more action potentials . so this is how the glomus cell helps to detect oxygen . and in fact , it also...
why is it pressure of oxygen / carbon dioxides are the causes ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
this is really interesting . our cell is depolarizing . it can depolarize .
so , what would be the name of the actual neurotransmitter that is released as a response to the glomus cell depolarizing ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
and now i want to remind you that there 's this little formula . there 's this formula where carbon dioxide binds with water , and it forms h2co3 . and that 's going to break down into bicarbonate and a proton .
in h2co3 what does the 3 stand for ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
so this is how the glomus cell helps to detect oxygen . and in fact , it also detects carbon dioxide . because , remember , this cell is going to be making carbon dioxide .
if someone had carbon monoxide poisoning , would this affect the interpretation of the chemoreceptors ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
and if you could do this in one minute , if you could pour out this bottle in one minute , imagine how wet this tomato 's going to get , how much profusion , in a sense , this tomato is going to get . that is how much profusion your carotid body gets . so it really puts it in perspective how much blood flow 's going in...
for instance , if there was higher amount of circulating 02 ( not bound to hbg because the co is.. ) would the receptors incorrectly perceive this as the body having too much o2 and then communicate to the cns that our o2 level is high ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
these things are called glomus cells . i had initially misstated it as a globus cell . but actually it 's an m -- glomus .
does the globus cell die when it depolarizes and releases its neurotransmitters ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
and my red blood cell , of course , has some hemoglobin in it , which is a protein . and this protein has got some oxygen bound to it . i 'm going to draw little blue oxygen molecules . and of course , there 's some oxygen out here in the plasma itself as well .
the cell lets the neurotransmitter know there is too little oxygen , so what happens on the cellular level when there is too much oxygen ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
so this is how the glomus cell helps to detect oxygen . and in fact , it also detects carbon dioxide . because , remember , this cell is going to be making carbon dioxide .
also are there any problems when there is very low amounts of carbon dioxide ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
because what our cell is going to be able to do is start to detect low oxygen levels . low oxygen levels in the glomus cell tells this cell that , actually , there are probably low levels in the blood . and when the levels are low , this cell is going to depolarize .
would the heart be considered the organ that measures the oxygen levels in our blood or would that be the kidney ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
and specifically they have a name . these things are called glomus cells . i had initially misstated it as a globus cell .
do glomus cells only detect plasma o2 or also the amount that is carried in the rbc ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
and that 's going to help regulate our blood pressure . now , in this video , we 're actually going to focus on chemoreceptors . chemoreceptors are also important in giving us information , but they 're going to give us information about things like oxygen levels , carbon dioxide levels , ph of the blood , things like ...
do you have a video explaining clearly then what happens during the hypoxic drive of a patient with copd ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
and as a result , carbon dioxide starts building up . the tissue starts gathering more and more co2 , because it ca n't go anywhere . and this glomus cell is going to say , hey , wait a second .
at 8 ; 10 , i ca n't understand how high pco2 & low po2 cause the same thing ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
and if the oxygen levels fall really low , let 's say they get dangerously low , where the cell is very unhappy , then you 're going to get much more neurotransmitter getting dumped out , and you 're going to get many more action potentials . so this is how the glomus cell helps to detect oxygen . and in fact , it also...
what neurotransmiter does the glomus cell secrete ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
and really , the same thing is going on on the aorta side . so on the aorta side , you 've got little branches coming off of the aorta , of course . and these branches are going to branch again , and again , and again , and again .
baroreceptors , i 've been taught that they are located in internal carotis , not only in the aorta arch ?
i 'm going to quickly sketch out the human heart . we 're also going to label some vessels coming off of it . so the big vessel , of course , is the aorta . this is the giant aortic arch . and the aortic arch has a couple of key branches that go , for example , up to the head and neck . it has other branches as well th...
so a high proton concentration -- i 'm going to put it in brackets , to indicate concentration . or another way of saying that would be a low ph . so these are the things that are going to make our glomus cell send off more action potentials .
why does many protons make for a low ph ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
now we know where this is going to go . i could do the long division again . t is going to be equal to 42,840 divided 210 , which is equal to 204 .
how does sal do that complex division using mental math ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects .
if a house 's property taxes are 3 % , what is the distance of that house from the school ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
and now you can divide both sides by 210 . now we know where this is going to go . i could do the long division again .
so in a different context of a question how do we know we are supposed to use parenthesis ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for .
the problem asks how many trees did mcdonald initially start with ... should n't the answer be 204 + 5 = 209 ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
so this is equal to 41,790 . so we 've set up our equation . now we just have to solve for t , the number of trees that macdonald initially had .
is there some sort of pattern that you can use when comes to different variations of the same linear equation problems ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
9 times 1 is 9 . 9 times 2 is 18 . and then we subtract again .
determine whether the ordered pairs given are solutions of the following linear inequality in two ( 5,2 ) ( 4 , 2 ) x+4y < 4 yes or no is the ordered pair 5 , 2 a solution of the linear inequality ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
remember , whatever we have to do to one side , we have to do the other . otherwise , the equality would n't be equal anymore . they were equal before adding 5 , so if you want them to still be equal , you have to do the same thing to both sides .
how would you do this : when a number n is increased by 25 % and 11 is added , the result is 51 ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
and then you would have ended up with -- let me do another alternate way of doing it . 210 times t minus 5 times 210 . actually , let me just multiply it out so we save some space .
why did n't you just take 210 away from 5 then you would of got 204 ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ?
maria 20 apples and oranges.apples cost .40 $ and oranges cost .35 $ how many of each fruit did maria bought ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
so this is equal to 41,790 . so we 've set up our equation . now we just have to solve for t , the number of trees that macdonald initially had .
what is the linear equation ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
and then you would have ended up with -- let me do another alternate way of doing it . 210 times t minus 5 times 210 . actually , let me just multiply it out so we save some space .
9 sal says that number of trees ( t-5 ) times number of oranges per trees ( 210 ) , so when in math we divide instead of multiplying and why not it is 210/ ( t-5 ) ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
actually , i will do it both ways just to show that you could do it both ways . so the first way , i 'm going to divide both sides by 210 . the left-hand side simplifies to t minus 5 .
it is able to block the sun because it is way father and the sun might be smaller than the sun , but how much light does the moon receive and how bright it is ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for .
now we will come up with a function telling us how many units a factory can produce depending on how many skilled workers and how many unskilled workers there are ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
and then you would have ended up with -- let me do another alternate way of doing it . 210 times t minus 5 times 210 . actually , let me just multiply it out so we save some space .
i do n't understand why you put 210 outside of the ( t-5 ) ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
it does not going into 41 . it goes into 417 one time , because two times would be 420 -- one time . 1 times 210 is 210 .
how do you distinguish between two in the word problem ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects .
what was the maximum height , in feet , of the ball above the ground after it was kicked ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
let 's let t equal what they 're asking is for . so this is the number of trees initially . so he starts off with t trees , but then they tell us that he has to cut down 5 trees to control the insects .
the product of 8 and a number increase by 6 is 104 what is the number ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects .
is there something online to help people form equations from word problems ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
now we know where this is going to go . i could do the long division again . t is going to be equal to 42,840 divided 210 , which is equal to 204 .
why did sal have to use his own division ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
so the left-hand side becomes t. i 'll do the t in that purple color . and the right-hand side becomes 204 . so he started off with 204 trees .
the current sum of ages of anjli and aarti is 49.how old is aarti right now ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ?
why did mcdonald need so many oranges ?
macdonald had a farm with a certain number of orange trees . he had to cut down 5 trees to control the insects . each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for . so this...
each of the remaining trees produced 210 oranges , producing a total harvest of 41,790 oranges . how many trees did macdonald 's farm have initially ? let 's let t equal what they 're asking is for .
how many solutions does this system of equations have ?
we 're in the very crowded and not very large room called the stanza della segnatura that is not only dense with people , but it 's dense with imagery . we 're looking at frescoes by raphael . painted during the high renaissance at the same time that michelangelo was painting the sistine chapel ceiling just a few doo...
plato was , in fact , aristotle 's teacher , but also because he holds one of his own books , the timaeus . and aristotle holds his book , the ethics . both of those books represent the contrasting philosophies of these two men .
who is the figure sprawled on the steps by himself in front of aristotle and plata , and what does he signify ?
we 're in the very crowded and not very large room called the stanza della segnatura that is not only dense with people , but it 's dense with imagery . we 're looking at frescoes by raphael . painted during the high renaissance at the same time that michelangelo was painting the sistine chapel ceiling just a few doo...
plato was , in fact , aristotle 's teacher , but also because he holds one of his own books , the timaeus . and aristotle holds his book , the ethics . both of those books represent the contrasting philosophies of these two men .
with so many of this cast being portraits of renaissance superstars , do we know is aristotle was a portrait ?
we 're in the very crowded and not very large room called the stanza della segnatura that is not only dense with people , but it 's dense with imagery . we 're looking at frescoes by raphael . painted during the high renaissance at the same time that michelangelo was painting the sistine chapel ceiling just a few doo...
and in fact , appropriate to his reincarnation here as euclid , bramante 's design for saint peter 's was based on a perfect geometry of circles and squares . and is really visible in the architecture that raphael constructed for the school of athens . here we see an architecture that is very bramantian , but also ve...
when raphael transferred his drawing of the school of athens to the wall for painting , what substance did he force through perforations in the paper ?
we 're in the very crowded and not very large room called the stanza della segnatura that is not only dense with people , but it 's dense with imagery . we 're looking at frescoes by raphael . painted during the high renaissance at the same time that michelangelo was painting the sistine chapel ceiling just a few doo...
and in fact , appropriate to his reincarnation here as euclid , bramante 's design for saint peter 's was based on a perfect geometry of circles and squares . and is really visible in the architecture that raphael constructed for the school of athens . here we see an architecture that is very bramantian , but also ve...
when raphael transferred his drawing of the school of athens to the wall for painting , what substance did he force through perforations in the paper ?
we 're in the very crowded and not very large room called the stanza della segnatura that is not only dense with people , but it 's dense with imagery . we 're looking at frescoes by raphael . painted during the high renaissance at the same time that michelangelo was painting the sistine chapel ceiling just a few doo...
we 're in the very crowded and not very large room called the stanza della segnatura that is not only dense with people , but it 's dense with imagery . we 're looking at frescoes by raphael .
how is reform shown throughout this piece ?
we 're in the very crowded and not very large room called the stanza della segnatura that is not only dense with people , but it 's dense with imagery . we 're looking at frescoes by raphael . painted during the high renaissance at the same time that michelangelo was painting the sistine chapel ceiling just a few doo...
and we can see representations of classical sculpture in the niches on the left , that is on the platonic side . we see apollo , the god of the sun , the god of music , the god of poetry , things that would be appropriate to the platonic . in turn on the right , we see athena , the god of war and wisdom , who presumab...
does her shield have the likeness of the nature god pan on it ?
we 're in the very crowded and not very large room called the stanza della segnatura that is not only dense with people , but it 's dense with imagery . we 're looking at frescoes by raphael . painted during the high renaissance at the same time that michelangelo was painting the sistine chapel ceiling just a few doo...
euclid is modeled actually on a friend of raphael 's and that 's bramante the great architect asked by pope julius ii to provide a new model for a new saint peter 's . and in fact , appropriate to his reincarnation here as euclid , bramante 's design for saint peter 's was based on a perfect geometry of circles and s...
at 9.13 , how do we know that it is , in fact , john the baptist and not some other prophet or saint ?
we 're in the very crowded and not very large room called the stanza della segnatura that is not only dense with people , but it 's dense with imagery . we 're looking at frescoes by raphael . painted during the high renaissance at the same time that michelangelo was painting the sistine chapel ceiling just a few doo...
but here , on the walls of the papal apartments , we get this image of sharing knowledge and the history of the accumulation of knowledge all with figures who move beautifully who in their bodies represent a gracefulness that is a reflection of their inner wisdom and knowledge . you 'll notice that raphael has not pla...
there is a story that raphael put himself in the painting , but where is he ?
we 're in the very crowded and not very large room called the stanza della segnatura that is not only dense with people , but it 's dense with imagery . we 're looking at frescoes by raphael . painted during the high renaissance at the same time that michelangelo was painting the sistine chapel ceiling just a few doo...
and also imagine quiet which is hard to do here , and an environment of learning where you could look up at what raphael painted here on the four walls which are the four branches of human knowledge , philosophy , having to do with things of this world . the philosophy at this time also meant what we know call the sc...
the speaker throws out a lot of art terms i do n't know , could someone explain ?
we 're in the very crowded and not very large room called the stanza della segnatura that is not only dense with people , but it 's dense with imagery . we 're looking at frescoes by raphael . painted during the high renaissance at the same time that michelangelo was painting the sistine chapel ceiling just a few doo...
virtually , every known great figure , but let 's start with the two in the center . we can tell plato from aristotle because plato is older . plato was , in fact , aristotle 's teacher , but also because he holds one of his own books , the timaeus .
why did raphael place him on team plato ?
we 're in the very crowded and not very large room called the stanza della segnatura that is not only dense with people , but it 's dense with imagery . we 're looking at frescoes by raphael . painted during the high renaissance at the same time that michelangelo was painting the sistine chapel ceiling just a few doo...
what a moment in the high renaissance all commissioned thanks to pope julius ii . and think about what it means for theology to be presented equally with human knowledge . it is this extraordinarily liberal moment in church history .
quick question- did all the later popes like this equality of the human knowledge and theology or did some oppose it ?
we 're in the very crowded and not very large room called the stanza della segnatura that is not only dense with people , but it 's dense with imagery . we 're looking at frescoes by raphael . painted during the high renaissance at the same time that michelangelo was painting the sistine chapel ceiling just a few doo...
so we have dozens of figures here without any sense of stiffness or repetition . raphael , like leonardo , in the last supper divides the figures into groups . each figure overlaps and moves easily between and amongst the others .
when was the site last updated ?
we 're in the very crowded and not very large room called the stanza della segnatura that is not only dense with people , but it 's dense with imagery . we 're looking at frescoes by raphael . painted during the high renaissance at the same time that michelangelo was painting the sistine chapel ceiling just a few doo...
and in fact , appropriate to his reincarnation here as euclid , bramante 's design for saint peter 's was based on a perfect geometry of circles and squares . and is really visible in the architecture that raphael constructed for the school of athens . here we see an architecture that is very bramantian , but also ve...
why is it entitle `` the school of athens '' ?
we 're in the very crowded and not very large room called the stanza della segnatura that is not only dense with people , but it 's dense with imagery . we 're looking at frescoes by raphael . painted during the high renaissance at the same time that michelangelo was painting the sistine chapel ceiling just a few doo...
and so it 's so interesting that raphael is paying homage to michelangelo the great artist here personifying heraclitus , the philosopher who believed that all things were always in flux . that figure of heraclitus was actually added later . raphael finished the frescoe , added some wet plaster , and added in that fi...
who does the figure sprawled on the steps represent ?
we 're in the very crowded and not very large room called the stanza della segnatura that is not only dense with people , but it 's dense with imagery . we 're looking at frescoes by raphael . painted during the high renaissance at the same time that michelangelo was painting the sistine chapel ceiling just a few doo...
this idea that there is a reality that transcends the reality that we see . compare that to the lower right where we see euclid , the figure we associate with geometry . in fact , he seems to be drawing a geometric diagram for some very eager students .
who is the figure with a beard on the right in red ?
let 's talk about arteriolosclerosis . i 'm going to first point out a couple of important big picture ideas . why it is arteriolosclerosis matter ? well , we know that it 's basically soft , flexible kind of vessels like this that are very elastic and can expand , becoming very rigid , firm like pipes . and this is ba...
so you 've got protein hanging out in the blood vessel . and these are serum proteins . serum , s-e-r-u-m , proteins .
what do serum proteins do when they 're not causing arteriolosclerosis ?
let 's talk about arteriolosclerosis . i 'm going to first point out a couple of important big picture ideas . why it is arteriolosclerosis matter ? well , we know that it 's basically soft , flexible kind of vessels like this that are very elastic and can expand , becoming very rigid , firm like pipes . and this is ba...
and you 'll learn as i go through it step by step a couple of interesting facts . so fact number one , we know that there 's a lot of glucose in the blood vessels . so lots of glucose in the blood vessels of someone with diabetes . so let 's draw in some glucose .
how does your body reflect the cells back into the body once being rotated through the blood vessels ?
let 's talk about arteriolosclerosis . i 'm going to first point out a couple of important big picture ideas . why it is arteriolosclerosis matter ? well , we know that it 's basically soft , flexible kind of vessels like this that are very elastic and can expand , becoming very rigid , firm like pipes . and this is ba...
and one of their jobs is to make sure that that basement membrane is doing a good job of forming a barrier . and that basement membrane becomes very leaky . so the basement membrane actually becomes thicker -- which is counterintuitive , right -- becomes thicker .
how can the basement membrane becomes leaky ?
let 's talk about arteriolosclerosis . i 'm going to first point out a couple of important big picture ideas . why it is arteriolosclerosis matter ? well , we know that it 's basically soft , flexible kind of vessels like this that are very elastic and can expand , becoming very rigid , firm like pipes . and this is ba...
and here is kind of fact number one , and that is that glucose can get into the endothelial cells without the help of insulin . so endothelial cells take in glucose without -- there 's the big catch -- without insulin . so they do n't need insulin to take in the glucose . there have other ways of getting the glucose in...
are there any other cells other than endothelial cells that do n't need insulin to take in glucose ?
let 's talk about arteriolosclerosis . i 'm going to first point out a couple of important big picture ideas . why it is arteriolosclerosis matter ? well , we know that it 's basically soft , flexible kind of vessels like this that are very elastic and can expand , becoming very rigid , firm like pipes . and this is ba...
so you 've got protein hanging out in the blood vessel . and these are serum proteins . serum , s-e-r-u-m , proteins .
do the serum proteins themselves physically do anything when in the t. media ?
for the past 12 weeks , we 've been investigating our living planet together , learning how it works on many levels , how populations of organisms interact , how communities thrive and ecosystems change , and how humans are wrecking the nice , perfectly functioning systems earth has been using for hundreds of thousands...
sometimes we get things wrong . for example , when you bring an invasive species into a place to eradicate another invasive species . sometimes you just end up with two invasive species on your hands , which collapses the ecosystem even more rapidly . the introduction of cane toads to australia in the 1930s to control ...
are there any examples of good invasive species which have benefited an ecosystem ?
for the past 12 weeks , we 've been investigating our living planet together , learning how it works on many levels , how populations of organisms interact , how communities thrive and ecosystems change , and how humans are wrecking the nice , perfectly functioning systems earth has been using for hundreds of thousands...
but if there were a population of 100 bears , the population would likely be able to survive for 200 years . something to note , ecology involves a lot of math . so if you 're interested in this , that 's just the way it is .
and , on an unrelated side note , is there a bacteria/archae/protist that is capable of turning co2 into oxygen and organic carbon ?
for the past 12 weeks , we 've been investigating our living planet together , learning how it works on many levels , how populations of organisms interact , how communities thrive and ecosystems change , and how humans are wrecking the nice , perfectly functioning systems earth has been using for hundreds of thousands...
now this stretch of the clark fork river runs unimpeded for the first time in over a century , and the restored area where the dam used to be is being turned into a state park . efforts like this show us conservation biology and restoration ecology in action . conservation biology involves measuring the biodiversity of...
can someone please explain the difference between conservation and restoration ecology along with some examples ?
for the past 12 weeks , we 've been investigating our living planet together , learning how it works on many levels , how populations of organisms interact , how communities thrive and ecosystems change , and how humans are wrecking the nice , perfectly functioning systems earth has been using for hundreds of thousands...
now this stretch of the clark fork river runs unimpeded for the first time in over a century , and the restored area where the dam used to be is being turned into a state park . efforts like this show us conservation biology and restoration ecology in action . conservation biology involves measuring the biodiversity of...
which country is devoting , or spending the most on conservation as well as restoration ecology ?
for the past 12 weeks , we 've been investigating our living planet together , learning how it works on many levels , how populations of organisms interact , how communities thrive and ecosystems change , and how humans are wrecking the nice , perfectly functioning systems earth has been using for hundreds of thousands...
and most of it washed into the reservoir created by the milltown dam . i mean , actually it was lucky that the dam was there -- it had only been completed six months before -- or the whole river system all the way to the pacific ocean would have been a toxic mess . as it happened , though , only about 160 kilometers of...
0 would n't getting the dam out of the way release the rest of the toxic copper sediments ?
for the past 12 weeks , we 've been investigating our living planet together , learning how it works on many levels , how populations of organisms interact , how communities thrive and ecosystems change , and how humans are wrecking the nice , perfectly functioning systems earth has been using for hundreds of thousands...
yet another , somewhat more invasive , restoration method is biological augmentation . rather than removing harmful substances , this involves adding organisms to the ecosystem to restore materials that are gone . plants that help fix nitrogen , like beans , acacia trees , and lupine , are often used to replenish nitro...
how long does it take to restore an ecosystem ?
for the past 12 weeks , we 've been investigating our living planet together , learning how it works on many levels , how populations of organisms interact , how communities thrive and ecosystems change , and how humans are wrecking the nice , perfectly functioning systems earth has been using for hundreds of thousands...
yet another , somewhat more invasive , restoration method is biological augmentation . rather than removing harmful substances , this involves adding organisms to the ecosystem to restore materials that are gone . plants that help fix nitrogen , like beans , acacia trees , and lupine , are often used to replenish nitro...
what is an adaptation that organisms in the aphotic zone might have ?
for the past 12 weeks , we 've been investigating our living planet together , learning how it works on many levels , how populations of organisms interact , how communities thrive and ecosystems change , and how humans are wrecking the nice , perfectly functioning systems earth has been using for hundreds of thousands...
sometimes you just end up with two invasive species on your hands , which collapses the ecosystem even more rapidly . the introduction of cane toads to australia in the 1930s to control beetles is a particularly infamous example . not only are they everywhere now , but because they 're toxic , they 're poisoning native...
kill off all the cane toad eating dingoes ?
for the past 12 weeks , we 've been investigating our living planet together , learning how it works on many levels , how populations of organisms interact , how communities thrive and ecosystems change , and how humans are wrecking the nice , perfectly functioning systems earth has been using for hundreds of thousands...
sometimes we get things wrong . for example , when you bring an invasive species into a place to eradicate another invasive species . sometimes you just end up with two invasive species on your hands , which collapses the ecosystem even more rapidly . the introduction of cane toads to australia in the 1930s to control ...
are there any examples of good invasive species which have benefited an ecosystem ?
for the past 12 weeks , we 've been investigating our living planet together , learning how it works on many levels , how populations of organisms interact , how communities thrive and ecosystems change , and how humans are wrecking the nice , perfectly functioning systems earth has been using for hundreds of thousands...
but if there were a population of 100 bears , the population would likely be able to survive for 200 years . something to note , ecology involves a lot of math . so if you 're interested in this , that 's just the way it is .
and , on an unrelated side note , is there a bacteria/archae/protist that is capable of turning co2 into oxygen and organic carbon ?
for the past 12 weeks , we 've been investigating our living planet together , learning how it works on many levels , how populations of organisms interact , how communities thrive and ecosystems change , and how humans are wrecking the nice , perfectly functioning systems earth has been using for hundreds of thousands...
and finally , you have to get at what 's causing the decline and figure out how to address it . milltown dam actually gives us a good example of this process . in the winter of 1996 , authorities had to release some of the water behind the dam as an emergency measure because of a big ice floe in the river that was thre...
0 wouldnt the ice break the dam anyway so it looked to me either way the fish would die ?
for the past 12 weeks , we 've been investigating our living planet together , learning how it works on many levels , how populations of organisms interact , how communities thrive and ecosystems change , and how humans are wrecking the nice , perfectly functioning systems earth has been using for hundreds of thousands...
as it happened , though , only about 160 kilometers of the river was all toxic , messed up . a lot of it recuperated over time . but all that nasty hazardous waste was still sitting behind milltown dam .
why did the toads that they talked about at the time of why did it poison every thing in its path ?
( lively piano music ) : we 're on the 4th floor of the museum of modern art in new york , and we 're looking at robert rauschenberg 's , `` bed . '' this is a combine , not quite a sculpture , not quite a painting , from 1955 . : so , combine means a combination of painting and sculpture ? : well , johns and rausch...
this is a combine , not quite a sculpture , not quite a painting , from 1955 . : so , combine means a combination of painting and sculpture ? : well , johns and rauschenberg were actually thinking about their art as between art and life , and what is that narrow space between the two ?
so a combine is always something that 's more of a painting and less of a sculpture , as is the case here , or could it be a work that more readily resembles a sculpture , but also has elements of painting ?
( lively piano music ) : we 're on the 4th floor of the museum of modern art in new york , and we 're looking at robert rauschenberg 's , `` bed . '' this is a combine , not quite a sculpture , not quite a painting , from 1955 . : so , combine means a combination of painting and sculpture ? : well , johns and rausch...
: so , combine means a combination of painting and sculpture ? : well , johns and rauschenberg were actually thinking about their art as between art and life , and what is that narrow space between the two ? : instead of thinking about it between painting and sculpture between these two things that symbolize fine ar...
what challenges to conserving of art are presented when the art is made from things like pillows , quilts , sheets and housepaint ?
( lively piano music ) : we 're on the 4th floor of the museum of modern art in new york , and we 're looking at robert rauschenberg 's , `` bed . '' this is a combine , not quite a sculpture , not quite a painting , from 1955 . : so , combine means a combination of painting and sculpture ? : well , johns and rausch...
what we 're looking at is , in fact , the stuff of a real bed . we 're looking at a real pillow . we 're looking at a real pillowcase , and a handmade quilted blanket , sheets , but if you look closely , you 're also seeing pencil and paint .
to use artifacts from the real world in their work ?
we 've already seen scenarios where we start with a differential equation and then we generate a slope field that describes the solutions to the differential equation and then we use that to visualize those solutions . what i want to do in this video is do an exercise that takes us the other way , start with a slope f...
so , i 'm feeling pretty good about this , especially if we can knock this one out here , if we can knock that one out . so , dy/dx is equal to x over y . well , then when x equals one and y equals one , dy/dx would be equal to one , and this slope looks larger than one .
dy/dx = x+y -y dy = x dx 1/2 y^2 = 1/2x^2 + c1 then use an initial value to solve for the constant , which i did for 1 , -3 and ended up with y^2 = -x^2 + 10 am i even remotely on the right track here ?
we 've already seen scenarios where we start with a differential equation and then we generate a slope field that describes the solutions to the differential equation and then we use that to visualize those solutions . what i want to do in this video is do an exercise that takes us the other way , start with a slope f...
our derivative here looks negative . it looks like negative two , which is consistent with this yellow differential equation . the slope here is definitely not a positive one , so we could rule this one out as well .
how do you solve the differential equation if we ca n't separate the variables ?
we 've already seen scenarios where we start with a differential equation and then we generate a slope field that describes the solutions to the differential equation and then we use that to visualize those solutions . what i want to do in this video is do an exercise that takes us the other way , start with a slope f...
and it looks like if the solution contained , say , this point right over here , that would actually be a solution to the differential equation y is equal to negative x minus one and you can verify that . if y is equal to negative x minus one , then the x and negative x cancel out and you are just left with dy/dx is eq...
could n't you have just observed that the slop field vectors are level at ( 0,0 ) , ( 1 , -1 ) , ( 2 , -2 ) , which means y ' = 0 at those points thus y ' = x + y ?
we 've already seen scenarios where we start with a differential equation and then we generate a slope field that describes the solutions to the differential equation and then we use that to visualize those solutions . what i want to do in this video is do an exercise that takes us the other way , start with a slope f...
and now that we 've done it , we can actually think about well , okay , what are the solutions for this differential equation going to look like . well , it depends where they start or what points they contain . if you have a solution that contains that point , it looks like it might do something like this .
what does sal mean when he said the solution depends on the points it contains ?
we 've already seen scenarios where we start with a differential equation and then we generate a slope field that describes the solutions to the differential equation and then we use that to visualize those solutions . what i want to do in this video is do an exercise that takes us the other way , start with a slope f...
if you have a solution that contains that point , it looks like it might do something like this . if you had a solution that contained this point , it might do something like that . and , of course , it keeps going .
the shape of the graph is depended on the starting point and anything else ?
we 've already seen scenarios where we start with a differential equation and then we generate a slope field that describes the solutions to the differential equation and then we use that to visualize those solutions . what i want to do in this video is do an exercise that takes us the other way , start with a slope f...
and you can also see what is happening here . when dy/dx is equal to x plus y , you would expect that as x increases for a given y your slope would increase and as y increases for a given x your slope increases . and we see that .
a man and his dog are runninng on a straight beach.at a given point in time the dog is 12m from his owner who strats running in a direction perpendicular to the beach with a certain constant speed.the dog runs twice as fast and always towards his owner.where do the man and and his dog meet ?