Answer
The solution set is $\color{blue}{\left\{-3, 4\right\}}$.
Work Step by Step
Factor the trinomial:
$(x-4)(x+3)=0$
Equate each factor to $0$:
$x-4 = 0 \text{ or } x+3=0$
Solve each equation above :
$x-4 = 0
\\x-4+4=0+4
\\x=4$
or
$x+3-3=0-3
\\x=-3$
Thus, the solution set is $\color{blue}{\left\{-3, 4\right\}}$.
