A=(2x+3)(5x-8)

Solution for A=(2x+3)(5x-8) equation:

=(2A+3)(5A-8)

We move all terms to the left:

-((2A+3)(5A-8))=0

We multiply parentheses ..

-((+10A^2-16A+15A-24))=0


We calculate terms in parentheses: -((+10A^2-16A+15A-24)), so:

(+10A^2-16A+15A-24)

We get rid of parentheses

10A^2-16A+15A-24

We add all the numbers together, and all the variables

10A^2-1A-24

Back to the equation:

-(10A^2-1A-24)


We get rid of parentheses

-10A^2+1A+24=0

We add all the numbers together, and all the variables

-10A^2+A+24=0

a = -10; b = 1; c = +24;
Δ = b2-4ac
Δ = 12-4·(-10)·24
Δ = 961
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{961}=31$
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-31}{2*-10}=\frac{-32}{-20}
=1+3/5
$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+31}{2*-10}=\frac{30}{-20}
=-1+1/2
$