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

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

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

We move all terms to the left:

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

We multiply parentheses ..

-((+10A^2+15A-4A-6))=0


We calculate terms in parentheses: -((+10A^2+15A-4A-6)), so:

(+10A^2+15A-4A-6)

We get rid of parentheses

10A^2+15A-4A-6

We add all the numbers together, and all the variables

10A^2+11A-6

Back to the equation:

-(10A^2+11A-6)


We get rid of parentheses

-10A^2-11A+6=0

a = -10; b = -11; c = +6;
Δ = b2-4ac
Δ = -112-4·(-10)·6
Δ = 361
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{361}=19$
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-11)-19}{2*-10}=\frac{-8}{-20}
=2/5
$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-11)+19}{2*-10}=\frac{30}{-20}
=-1+1/2
$