Answer
$\color{blue}{\left\{-3\sqrt3, 3\sqrt3\right\}}$
Work Step by Step
Add $x^2$ to both sides to obtain:
$27=x^2
\\x^2=27$
RECALL:
If $x^2=a$, then taking the square root of both sides gives $x = \pm \sqrt{a}$.
Take the square root of both sides of the given equation to obtain:
$\sqrt{x^2}=\pm \sqrt{27}
\\x =\pm \sqrt{9(3)}
\\x=\pm\sqrt{3^2(3)}
\\x=\pm 3\sqrt{3}$
Thus, the solution set is $\color{blue}{\left\{-3\sqrt3, 3\sqrt3\right\}}$.
