A=6x(2x+6)

Solution for A=6x(2x+6) equation:

=6A(2A+6)

We move all terms to the left:

-(6A(2A+6))=0


We calculate terms in parentheses: -(6A(2A+6)), so:

6A(2A+6)

We multiply parentheses

12A^2+36A

Back to the equation:

-(12A^2+36A)


We get rid of parentheses

-12A^2-36A=0

a = -12; b = -36; c = 0;
Δ = b2-4ac
Δ = -362-4·(-12)·0
Δ = 1296
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1296}=36$
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-36)-36}{2*-12}=\frac{0}{-24}
=0
$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-36)+36}{2*-12}=\frac{72}{-24}
=-3
$