Answer
{$-7,4$}
Work Step by Step
Using the rules of factoring trinomials to factor the polynomial, we obtain:
$x^{2}+3x-28=0$
$x^{2}-4x+7x-28=0$
$x(x-4)+7(x-4)=0$
$(x-4)(x+7)=0$
Now, we equate the two factors to zero and solve:
$(x-4)(x+7)=0$
$(x-4)=0$ or $(x+7)=0$
$x=4$ or $x=-7$
Therefore, the solution set is {$-7,4$}.
