Answer
$\left\{-4-\sqrt7, -4+\sqrt7\right\}$
Work Step by Step
Divide 3 on both sides of the equation to obtain:
$(x+4)^2=7$
Take the square root of both sides to obtain:
$x+4 = \pm \sqrt{7}$
Add $-4$ on both sides of the equation to obtain:
$x=-4 \pm \sqrt{7}$
Thus, the solution set of the given equation is $\left\{-4-\sqrt7, -4+\sqrt7\right\}$.