Answer
$$x=4,\:x=-7,\:x=12$$
Work Step by Step
We solve the given expression by using the rules of Algebra to isolate the variable on one side of the equation. Doing this, we find:
$$ \left(x-12\right)\left(x^2+3x-28\right)=0\\ \left(x-4\right)\left(x+7\right)\left(x-12\right)=0\\ x=4,\:x=-7,\:x=12$$
