2(-x+9)(4x+4)=0

Solution for 2(-x+9)(4x+4)=0 equation:

2(-x+9)(4x+4)=0

We add all the numbers together, and all the variables

2(-1x+9)(4x+4)=0

We multiply parentheses ..

2(-4x^2-4x+36x+36)=0

We multiply parentheses

-8x^2-8x+72x+72=0

We add all the numbers together, and all the variables

-8x^2+64x+72=0

a = -8; b = 64; c = +72;
Δ = b2-4ac
Δ = 642-4·(-8)·72
Δ = 6400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6400}=80$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(64)-80}{2*-8}=\frac{-144}{-16}
=+9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(64)+80}{2*-8}=\frac{16}{-16}
=-1
$