A=3x*(5x+8)

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

=3A(5A+8)

We move all terms to the left:

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


We calculate terms in parentheses: -(3A(5A+8)), so:

3A(5A+8)

We multiply parentheses

15A^2+24A

Back to the equation:

-(15A^2+24A)


We get rid of parentheses

-15A^2-24A=0

a = -15; b = -24; c = 0;
Δ = b2-4ac
Δ = -242-4·(-15)·0
Δ = 576
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{576}=24$
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-24)-24}{2*-15}=\frac{0}{-30}
=0
$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-24)+24}{2*-15}=\frac{48}{-30}
=-1+3/5
$