Answer
The solution set is $\left\{-10, 0, 10\right\}$.
Work Step by Step
Factor out $4x$ to find:
$4x(x^2-100)=0
\\4x(x^2-10^2)=0$
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 find:
$4x(x-10)(x+10)=0$
Equate each factor to 0 then solve each equation to find:
$4x=0 \text{ or } x-10=0 \text{ or } x+10 = 0\\
x=0 \text{ or } x=10 \text{ or } x=-10$
The solution set is $\left\{-10, 0, 10\right\}$.
