Question

The graph of a function shown below. Use the graph of the function to find its average rate of change from x=to x = 4; x = 8

Answer 1

Recall that the average rate of change between a and b is given by the following formula:

$\frac{f(a)-f(b)}{a-b}\text{.}$

From the graph we get:

$\begin{gathered} f(4)=-1, \\ f(8)=-9. \end{gathered}$

Therefore, the average rate of change from x=4 to x=8 is:

$\frac{f(4)-f(8)}{4-8}=\frac{-1-(-9_{})}{-4}=\frac{-1+9}{-4}=\frac{8}{-4}=-2.$

Answer: -2.