Answer
$\left\{−4,4\right\}$
Work Step by Step
Add 13 to both sides:
$4|x|−13+13=3+13
\\4|x|=16$
Divide 4 to both sides:
$\dfrac{4|x|}{4}=\dfrac{16}{4}
\\|x|=4$
RECALL:
$|x|=a \longrightarrow x=a \text{ or } x=−a$
Thus,
$|x|=4 \longrightarrow x=4 \text{ or } x=−4$
Therefore, the solution set is:
$\left\{−4,4\right\}$
