-3x(2x-8)=12

Solution for -3x(2x-8)=12 equation:

-3x(2x-8)=12

We move all terms to the left:

-3x(2x-8)-(12)=0

We multiply parentheses

-6x^2+24x-12=0

a = -6; b = 24; c = -12;
Δ = b2-4ac
Δ = 242-4·(-6)·(-12)
Δ = 288
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:

$\sqrt{\Delta}=\sqrt{288}=\sqrt{144*2}=\sqrt{144}*\sqrt{2}=12\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(24)-12\sqrt{2}}{2*-6}=\frac{-24-12\sqrt{2}}{-12}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(24)+12\sqrt{2}}{2*-6}=\frac{-24+12\sqrt{2}}{-12}
$