Answer
The solution set is $\{-6,6\}$.
Work Step by Step
The given expression is
$\Rightarrow x^2-36=0$
Add $36$ to each side.
$\Rightarrow x^2-36+36=0+36$
Simplify.
$\Rightarrow x^2=36$
$36\geq0$ is a nonnegative number.
Use the square root method.
$\Rightarrow x=\pm\sqrt {36}$
Use $\sqrt {36}=6$.
$\Rightarrow x=\pm 6$
Hence, the solution set is $\{-6,6\}$.
