Answer
(a) minimum: (-1,-4), maxima: (-4,-1) and (3,4)
(b) increasing: $(-\infty,\ -4)$ and $(-1,3)$
decreasing: $(-4,\ -1)$ and $(3,\ \infty)$
Work Step by Step
(a) We see from the graph that the function $f$ has a local minimum at (-1,-4) and two local maxima at (-4,-1) and (3,4).
(b) We see from the graph that the function $f$ is increasing on the intervals $(-\infty,\ -4)$ and $(-1,3)$ and decreasing on the intervals $(-4,\ -1)$ and $(3,\ \infty)$.
