Answer
Calculate $f(a) $ and $f(b).$
average rate of change $=\displaystyle \frac{f(b)-f(a)}{b-a}$
Work Step by Step
The average rate of change of the function f between x=a and x=b
is the slope of the secant line between $(a, f(a))$ and $ (b, f(b)) :$
average rate of change $=\displaystyle \frac{f(b)-f(a)}{b-a}$
