A=2x+6x2

Solution for A=2x+6x2 equation:

=2A+6A^2

We move all terms to the left:

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

We get rid of parentheses

-6A^2-2A=0

a = -6; b = -2; c = 0;
Δ = b2-4ac
Δ = -22-4·(-6)·0
Δ = 4
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4}=2$
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-2}{2*-6}=\frac{0}{-12}
=0
$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+2}{2*-6}=\frac{4}{-12}
=-1/3
$