-2x(x-8)=-123

Solution for -2x(x-8)=-123 equation:

-2x(x-8)=-123

We move all terms to the left:

-2x(x-8)-(-123)=0

We add all the numbers together, and all the variables

-2x(x-8)+123=0

We multiply parentheses

-2x^2+16x+123=0

a = -2; b = 16; c = +123;
Δ = b2-4ac
Δ = 162-4·(-2)·123
Δ = 1240
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:

$\sqrt{\Delta}=\sqrt{1240}=\sqrt{4*310}=\sqrt{4}*\sqrt{310}=2\sqrt{310}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(16)-2\sqrt{310}}{2*-2}=\frac{-16-2\sqrt{310}}{-4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(16)+2\sqrt{310}}{2*-2}=\frac{-16+2\sqrt{310}}{-4}
$