Answer
a) $(-\infty,-1)\cup(4,\infty)$
(b) $[-1,4]$
Work Step by Step
a) We observe where the graph falls below the x-axis. This happens before $-1$ and after $4$. Thus, we get the interval: $(-\infty,-1)\cup(4,\infty)$
(b) The function is above the x-axis on the opposite interval of (a). This is the inteval: $[-1,4]$