A=2x^2+36x

Solution for A=2x^2+36x equation:

=2A^2+36A

We move all terms to the left:

-(2A^2+36A)=0

We get rid of parentheses

-2A^2-36A=0

a = -2; b = -36; c = 0;
Δ = b2-4ac
Δ = -362-4·(-2)·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*-2}=\frac{0}{-4}
=0
$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-36)+36}{2*-2}=\frac{72}{-4}
=-18
$