(8x-9)(4x+7)=0

Solution for (8x-9)(4x+7)=0 equation:

(8x-9)(4x+7)=0

We multiply parentheses ..

(+32x^2+56x-36x-63)=0

We get rid of parentheses

32x^2+56x-36x-63=0

We add all the numbers together, and all the variables

32x^2+20x-63=0

a = 32; b = 20; c = -63;
Δ = b2-4ac
Δ = 202-4·32·(-63)
Δ = 8464
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{8464}=92$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(20)-92}{2*32}=\frac{-112}{64}
=-1+3/4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+92}{2*32}=\frac{72}{64}
=1+1/8
$