Answer
$x=\{ -2\sqrt{3},2\sqrt{3} \}$
Work Step by Step
Using the properties of equality, the given equation, $
3x^2=36
,$ is equivalent to
\begin{align*}
\dfrac{3x^2}{3}&=\dfrac{36}{3}
\\\\
x^2&=12
.\end{align*}
Getting the square root of both sides (Square Root Property), the equation above is equivalent to
\begin{align*}
x&=\pm\sqrt{12}
\\
x&=\pm\sqrt{4\cdot3}
\\
x&=\pm2\sqrt{3}
.\end{align*}
Hence, the solutions are $
x=\{ -2\sqrt{3},2\sqrt{3} \}
$.