(4x-4)(x)=80

Solution for (4x-4)(x)=80 equation:

(4x-4)(x)=80

We move all terms to the left:

(4x-4)(x)-(80)=0

We multiply parentheses

4x^2-4x-80=0

a = 4; b = -4; c = -80;
Δ = b2-4ac
Δ = -42-4·4·(-80)
Δ = 1296
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1296}=36$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4)-36}{2*4}=\frac{-32}{8}
=-4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+36}{2*4}=\frac{40}{8}
=5
$