standard_description: Interpret the equation y = mx + b as defining a linear function, whose graph is a straight line; give examples of functions that are not linear. For example, the function A = s2 giving the area of a square as a function of its side length is not linear because its graph contains the points (1,1), (2,4) and (3,9), which are not on a straight line.
problem_activity: Task
Complete the table. In the third column, show your work as demonstrated. What do you notice about the 3rd column?
{"table": [{"tbody": [{"tr": [{"th": [{"_value": "$x$"}, {"_value": "$y=2x+5$"}, {"_value": "$\\Delta y$"}]}, {"td": [{"_value": "1"}, {"_value": "7"}, {"_value": "----"}]}, {"td": [{"_value": "2"}, {"_value": "9"}, {"_value": "9 - 7 = 2"}]}, {"td": [{"_value": "3"}, {}, {}]}, {"td": [{"_value": "4"}, {}, {}]}, {"td": [{"_value": "5"}, {}, {}]}]}]}]}
Complete the table, showing your work as above. What do you notice about the 3rd column? What is the graphical interpretation of this?
{"table": [{"tbody": [{"tr": [{"th": [{"_value": "$x$"}, {"_value": "$y=ax+b$"}, {"_value": "$\\Delta y$"}]}, {"td": [{"_value": "1"}, {"_value": "$a\\cdot\u00a01 +b$"}, {"_value": "---"}]}, {"td": [{"_value": "2"}, {"_value": "$a \\cdot\u00a02 +b$"}, {"_value": "$a\\cdot\u00a02+b - (a\\cdot\u00a01 + b) = a$"}]}, {"td": [{"_value": "3"}, {}, {}]}, {"td": [{"_value": "4"}, {}, {}]}, {"td": [{"_value": "5"}, {}, {}]}]}]}]}
Let $y=ax+b$. Let $x_0$ be any particular $x$-value. Show that if $x_0$ is increased by 1, the corresponding $\Delta y$ is a constant that does not depend on $x_0$. What is this constant?
Does (a) serve as an example of the result in (c) ? Explain.


aligns: no