#### Answer

$x=\pm4$

#### Work Step by Step

Since $x^2=a$ implies $x=\pm\sqrt{a}$ (the Square Root Property), then the solutions of the given equation, $
x^2=16
,$ are
\begin{array}{l}\require{cancel}
x=\pm\sqrt{16}
\\\\
x=\pm\sqrt{(4)^2}
\\\\
x=\pm4
.\end{array}