(2x-8)(x)=120

Solution for (2x-8)(x)=120 equation:

(2x-8)(x)=120

We move all terms to the left:

(2x-8)(x)-(120)=0

We multiply parentheses

2x^2-8x-120=0

a = 2; b = -8; c = -120;
Δ = b2-4ac
Δ = -82-4·2·(-120)
Δ = 1024
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1024}=32$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-32}{2*2}=\frac{-24}{4}
=-6
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+32}{2*2}=\frac{40}{4}
=10
$