Answer
$x=\pm3\sqrt{3}$
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=27
,$ are
\begin{array}{l}\require{cancel}
x=\pm\sqrt{27}
\\\\
x=\pm\sqrt{9\cdot3}
\\\\
x=\pm\sqrt{(3)^2\cdot3}
\\\\
x=\pm3\sqrt{3}
.\end{array}