Answer
$x=12 \text{ and } x=-8$
Work Step by Step
Subtract $100$ from each side:
$$x^2-4x-96=0$$
Factor the trinomial:
$$(x-12)(x+8)=0$$
Use the Zero-Product Property by equating each factor to zero, then solve each equation to obtain:
\begin{align*}
x-12&=0 &\text{or}& &x+8=0\\
x&=12 &\text{or}& &x=-8
\end{align*}
Thus, the solutions are $x=12 \text{ and } x=-8$.
