A=5x(3x+2)

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

=5A(3A+2)

We move all terms to the left:

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


We calculate terms in parentheses: -(5A(3A+2)), so:

5A(3A+2)

We multiply parentheses

15A^2+10A

Back to the equation:

-(15A^2+10A)


We get rid of parentheses

-15A^2-10A=0

a = -15; b = -10; c = 0;
Δ = b2-4ac
Δ = -102-4·(-15)·0
Δ = 100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{100}=10$
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-10)-10}{2*-15}=\frac{0}{-30}
=0
$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+10}{2*-15}=\frac{20}{-30}
=-2/3
$