(4x+8)(2x-8)=0

Solution for (4x+8)(2x-8)=0 equation:

(4x+8)(2x-8)=0

We multiply parentheses ..

(+8x^2-32x+16x-64)=0

We get rid of parentheses

8x^2-32x+16x-64=0

We add all the numbers together, and all the variables

8x^2-16x-64=0

a = 8; b = -16; c = -64;
Δ = b2-4ac
Δ = -162-4·8·(-64)
Δ = 2304
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2304}=48$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-16)-48}{2*8}=\frac{-32}{16}
=-2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-16)+48}{2*8}=\frac{64}{16}
=4
$