## Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

$18$
The average rate of change from $2$ to $4$ is given by $\frac{f(4)-f(2)}{4-2}$. Thus, the average rate of change from $2$ to $4$ is: $\dfrac{f(4)-f(2)}{4-2}\\$ $=\dfrac{3(4)^2-2 -(3(2)^2-2)}{2}\\$ $=\dfrac{36}{2}=18$