Answer
$(-\infty,0)\cup(4,\infty)$ or $\{x|x\lt0\ or\ x\gt4\}$.
Work Step by Step
Step 1. $x^2-4x\gt0 \longrightarrow x(x-4)\gt0$.
Step 2. Identify boundary points $x=0,4$ and form intervals $(-\infty,0),(0,4),(4,\infty)$.
Step 3. Choose test values $x=-1,1,5$ to test the inequality and get results $True,\ False,\ True$.
Step 4. Thus we have the solution $(-\infty,0)\cup(4,\infty)$ or $\{x|x\lt0\ or\ x\gt4\}$.
