Answer
(a)
Increasing on $(-4, -3.2)\cup(-1.4,1)\cup(2, 4)$,
Decreasing on $(-3.2, -1.4)\cup(1, 2)$
(b)
Absolute maximum at $(4,2)$.
Absolute minimum at $(-1.4, -1)$.
Local maximum at $(-3.2,1)$ and $(1,1)$.
Local minimum at $(-4,0)$ and $(2,0)$.
Work Step by Step
See image below.