Answer
$(-\infty,-4)\cup(-4,0)\cup(0,\infty)$
Work Step by Step
As an absolute value is greater or equal to zero and can not be negative, the solution set is all real numbers except $x^2+4x=0$ which gives $x=-4$ and $x=0$, thus the solution set is $(-\infty,-4)\cup(-4,0)\cup(0,\infty)$
