(-5x+5)(4x+4)=0

Solution for (-5x+5)(4x+4)=0 equation:

(-5x+5)(4x+4)=0

We multiply parentheses ..

(-20x^2-20x+20x+20)=0

We get rid of parentheses

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

We add all the numbers together, and all the variables

-20x^2+20=0

a = -20; b = 0; c = +20;
Δ = b2-4ac
Δ = 02-4·(-20)·20
Δ = 1600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1600}=40$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-40}{2*-20}=\frac{-40}{-40}
=1
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+40}{2*-20}=\frac{40}{-40}
=-1
$