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
Use the graph (for example, by marking specific points) to illustrate the statements in
(a)–(d).  If possible, label the coordinates of any points you draw.
[IMG]
$f(0) = 2$
$f(−3)=f(3)=f(9)=0$
$f(2) = g(2)$
$g(x)>f(x)$ for $x>2$


aligns: no