Chapter 4 - Applications of the Derivative - 4.2 What Derivatives Tell Us - 4.2 Exercises - Page 256: 16

See the graph.

Since $f'(-3)=0$ and sign of $f'(x)$ is changing from positive to negative around $-3$, so $f'(x)$ have local maxima at $x=-3$ , also $f'(1)=0$ and sign of $f'(x)$ ia changing from negative to positive , so $f'(x)$ have local minima at $x=1$.