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

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

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

We multiply parentheses ..

(+32x^2+56x-28x-49)=0

We get rid of parentheses

32x^2+56x-28x-49=0

We add all the numbers together, and all the variables

32x^2+28x-49=0

a = 32; b = 28; c = -49;
Δ = b2-4ac
Δ = 282-4·32·(-49)
Δ = 7056
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{7056}=84$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(28)-84}{2*32}=\frac{-112}{64}
=-1+3/4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(28)+84}{2*32}=\frac{56}{64}
=7/8
$