Answer
The solution set is $\left\{-4, 4\right\}$.
Work Step by Step
Add $-16$ to both sides to obtain:
$x^2-16=0
\\x^2-4^2=0$
RECALL:
A difference of two squares can be factored using the formula:
$a^2-b^2=(a-b)(a+b)$
Factor the difference of two squares to obtain:
$(x-4)(x+4)=0$
Equate each factor to 0, and then solve each equation to obtain:
$x-4=0 \text{ or } x+4 = 0
\\x=4 \text{ or } x=-4$
The solution set is $\left\{-4, 4\right\}$.
