3x(x+8)=-12

Solution for 3x(x+8)=-12 equation:

3x(x+8)=-12

We move all terms to the left:

3x(x+8)-(-12)=0

We add all the numbers together, and all the variables

3x(x+8)+12=0

We multiply parentheses

3x^2+24x+12=0

a = 3; b = 24; c = +12;
Δ = b2-4ac
Δ = 242-4·3·12
Δ = 432
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{432}=\sqrt{144*3}=\sqrt{144}*\sqrt{3}=12\sqrt{3}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(24)-12\sqrt{3}}{2*3}=\frac{-24-12\sqrt{3}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(24)+12\sqrt{3}}{2*3}=\frac{-24+12\sqrt{3}}{6}
$