Welcome to the World Wide Center of Mathematics College Algebra series. So today I'm going to be talking about subsets and this is a continuation of our set video which you can find in our College Algebra playlist. So what I have behind me is a defined set A with elements 1, 2, 5, 8, 17 and 102. And these don't have any real relationship with each other, they're just numbers that I picked. And so a subset, a subset is defined to be a set whose elements are found in another set. So for example, let's look at a subset lowercase A. We'll set this equal to 1, 2, 5. And so our definition is that the elements of a subset can be found in a different set. And so we've got elements 1, 2 and 5 in set lowercase A. And each of these can be found in our defined capital A set. So this is a subset of A. So this subset is a subset of capital A. And so let's look at another one. We'll do B this time. So B has elements 1, 8, 17, 102. And each of these elements can be found in set A. So B is a subset of A. And now let's look at another subset. We can do C. And C is equal to 1, 2, 3, 17. And so here, it's pretty obvious. We've got a 3 in our set C. And 3 is not found in A. So C is not a subset of A. This is the notation for when your set is not a subset of another set. And so what if we had, let's try set D. What if we had set D with elements 1, 2, 5, 8, 17 and 102. So set D has all of the elements that are in set A. In fact, set D is equal to A. But let's look at our definition of a subset again. A subset is any set whose elements are found in another set. And so all of the elements of set D are found in set A. So D is still a subset of A. And this one has notation that is a little different than the other sets. Because it's also equal to set A, we use our subset symbol as well as a line underneath. So D is a subset of A. Thank you for watching this Worldwide Center of Mathematics short on algebra. So be sure to click this button to subscribe to our channel so that you don't miss any new math videos. Click here to visit the playlist for the video that you just watched. And click on this button to visit centerofmath.org for even more math resources.