-3x(4x-8)=-36

Solution for -3x(4x-8)=-36 equation:

-3x(4x-8)=-36

We move all terms to the left:

-3x(4x-8)-(-36)=0

We add all the numbers together, and all the variables

-3x(4x-8)+36=0

We multiply parentheses

-12x^2+24x+36=0

a = -12; b = 24; c = +36;
Δ = b2-4ac
Δ = 242-4·(-12)·36
Δ = 2304
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2304}=48$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(24)-48}{2*-12}=\frac{-72}{-24}
=+3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(24)+48}{2*-12}=\frac{24}{-24}
=-1
$