(4x-8)(7x+8)=0

Solution for (4x-8)(7x+8)=0 equation:

(4x-8)(7x+8)=0

We multiply parentheses ..

(+28x^2+32x-56x-64)=0

We get rid of parentheses

28x^2+32x-56x-64=0

We add all the numbers together, and all the variables

28x^2-24x-64=0

a = 28; b = -24; c = -64;
Δ = b2-4ac
Δ = -242-4·28·(-64)
Δ = 7744
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{7744}=88$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-24)-88}{2*28}=\frac{-64}{56}
=-1+1/7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-24)+88}{2*28}=\frac{112}{56}
=2
$