Answer
$x=-4$ or $x=1$
Work Step by Step
Subtract $4$ from each side:
$x^2+3x-4=0$
Factor the trinomial to obtain:
$x^2+3x-4=0\\
(x+4)(x-1)=0$
Use the Zero-Product Property to obtain:
$x+4=0$ or $x-1=0$
Hence,
$x=-4$ or $x=1$