-3x(x+8)=8

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

-3x(x+8)=8

We move all terms to the left:

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

We multiply parentheses

-3x^2-24x-8=0

a = -3; b = -24; c = -8;
Δ = b2-4ac
Δ = -242-4·(-3)·(-8)
Δ = 480
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:

$\sqrt{\Delta}=\sqrt{480}=\sqrt{16*30}=\sqrt{16}*\sqrt{30}=4\sqrt{30}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-24)-4\sqrt{30}}{2*-3}=\frac{24-4\sqrt{30}}{-6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-24)+4\sqrt{30}}{2*-3}=\frac{24+4\sqrt{30}}{-6}
$