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.
8.F Functions
8.F.A Define, evaluate, and compare functions.