Answer
$(-\infty,-1]\cup[4,\infty)$
Work Step by Step
1. The domain requirement of the given function is $x^2-3x-4\ge0$ or $(x+1)(x-4)\ge0$
2. The $\ge$ sign requires that the solution be outside the region between the boundary points, thus the solution $(-\infty,-1]\cup[4,\infty)$
