Answer
$[-4,\infty)$
Work Step by Step
First I graph the function.
Then, according to the graph of the function: $f(x)\geq0$ in the interval $[-4,\infty)$ because the graph of the function is above or on the x-axis ($y=0$) on this interval.
$-4$ and $2$ are included because the inequality involves greater than or equal to.