A=(5x+8)(12x-8)

Solution for A=(5x+8)(12x-8) equation:

=(5A+8)(12A-8)

We move all terms to the left:

-((5A+8)(12A-8))=0

We multiply parentheses ..

-((+60A^2-40A+96A-64))=0


We calculate terms in parentheses: -((+60A^2-40A+96A-64)), so:

(+60A^2-40A+96A-64)

We get rid of parentheses

60A^2-40A+96A-64

We add all the numbers together, and all the variables

60A^2+56A-64

Back to the equation:

-(60A^2+56A-64)


We get rid of parentheses

-60A^2-56A+64=0

a = -60; b = -56; c = +64;
Δ = b2-4ac
Δ = -562-4·(-60)·64
Δ = 18496
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{18496}=136$
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-56)-136}{2*-60}=\frac{-80}{-120}
=2/3
$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-56)+136}{2*-60}=\frac{192}{-120}
=-1+3/5
$