Interpret the Equation y = mx + b as Defining a Linear Function
Standard 8.F.3 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.