## College Algebra 7th Edition

$(-\infty,\ 0] \cup\ [4,\ \infty)$
We see from the graph that the equation $y=x^{2}-4x$ lies above (i.e is greater than) the $x$-axis for $x\lt 0$ and for $x\gt 4$, i.e. $(-\infty,\ 0] \cup\ [4,\ \infty)$ .