Answer
a) $(-1,1)\cup(2,\infty)$.
b) $(-\infty,-1]\cup[1,2]$.
Work Step by Step
As we can see on the graph:
a) $f(x)<0$, in the intervals $(-1,1)\cup(2,\infty)$ because the graph of the function is below the x-axis (which is $y=f(x)=0$) on these intervals. $1$ and $2$ are not included because the inequality involves less than.
b) $f(x)\geq0,$ in the intervals $(-\infty,-1]\cup[1,2]$ because the graph of the function is above or on the the x-axis (which is $y=f(x)=0$) on these intervals. $-1$, $1$ and $2$ are included because the inequality involves greater than or equal to.
