Answer
$(-\infty,0]\cup[4,\infty)$
Work Step by Step
We are given the function:
$f(x)=x^2-4x$
Graph the function.
The solution of the inequality $f(x)\geq 0$ consists of the values of $x$ for which the graph of the function is above the $x$-axis.
Determine the zeroes of the function:
$x^2-4x=0\Rightarrow x(x-4)=0\Rightarrow x=0,x=4$
The solution of the inequality is:
$(-\infty,0]\cup[4,\infty)$
