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

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

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

We multiply parentheses ..

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

We get rid of parentheses

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

We add all the numbers together, and all the variables

63x^2+7x-56=0

a = 63; b = 7; c = -56;
Δ = b2-4ac
Δ = 72-4·63·(-56)
Δ = 14161
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{14161}=119$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(7)-119}{2*63}=\frac{-126}{126}
=-1
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(7)+119}{2*63}=\frac{112}{126}
=8/9
$