Answer
(a) $(-\infty-1)U(-1,1)U(3,\infty)$.
(b) $[1,-2)U(-2,3]$.
Work Step by Step
(a) Based on the given graph, we can identify the solution for $f(x)\gt0$: $(-\infty-1)U(-1,1)U(3,\infty)$.
(b) Based on the given graph, we can identify the solution for $f(x)\le0$: $[1,-2)U(-2,3]$.
