-2x(10+6x)=-128

Solution for -2x(10+6x)=-128 equation:

-2x(10+6x)=-128

We move all terms to the left:

-2x(10+6x)-(-128)=0

We add all the numbers together, and all the variables

-2x(6x+10)-(-128)=0

We add all the numbers together, and all the variables

-2x(6x+10)+128=0

We multiply parentheses

-12x^2-20x+128=0

a = -12; b = -20; c = +128;
Δ = b2-4ac
Δ = -202-4·(-12)·128
Δ = 6544
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:

$\sqrt{\Delta}=\sqrt{6544}=\sqrt{16*409}=\sqrt{16}*\sqrt{409}=4\sqrt{409}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-4\sqrt{409}}{2*-12}=\frac{20-4\sqrt{409}}{-24}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+4\sqrt{409}}{2*-12}=\frac{20+4\sqrt{409}}{-24}
$