(7x-7)(8x+3)=0

Solution for (7x-7)(8x+3)=0 equation:

(7x-7)(8x+3)=0

We multiply parentheses ..

(+56x^2+21x-56x-21)=0

We get rid of parentheses

56x^2+21x-56x-21=0

We add all the numbers together, and all the variables

56x^2-35x-21=0

a = 56; b = -35; c = -21;
Δ = b2-4ac
Δ = -352-4·56·(-21)
Δ = 5929
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5929}=77$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-35)-77}{2*56}=\frac{-42}{112}
=-3/8
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-35)+77}{2*56}=\frac{112}{112}
=1
$