#### Answer

$x=\{-4,0\}$

#### Work Step by Step

$\bf{\text{Solution Outline:}}$
To solve the given inequality, $
|x^2+4x|\le0
,$ use the definition of absolute value to analyze the given inequality. Then use concepts of solving quadratic equations to find the values of $x.$
$\bf{\text{Solution Details:}}$
The absolute value of $x$, given by $|x|,$ is the distance of $x$ from $0,$ and hence is always a nonnegative number. Therefore, for any $x,$ the expression at the left, $
|x^2+4x|
,$ is nonnegative. The given inequality will only be satisfied when $
x^2+4x=0
.$
Factoring the $GCF=x,$ the factored form of the equation above is
\begin{array}{l}\require{cancel}
x(x+4)=0
.\end{array}
Equating each factor to zero (Zero Product Property), the solutions of the equation above are
\begin{array}{l}\require{cancel}
x=0
\\\\\text{OR}\\\\
x+4=0
.\end{array}
Solving the equations results to
\begin{array}{l}\require{cancel}
x=0
\\\\\text{OR}\\\\
x+4=0
\\\\
x=-4
.\end{array}
Hence, the solutions are $
x=\{-4,0\}
.$