(12-2x)*(6-2x)=36

Solution for (12-2x)*(6-2x)=36 equation:

(12-2x)(6-2x)=36

We move all terms to the left:

(12-2x)(6-2x)-(36)=0

We add all the numbers together, and all the variables

(-2x+12)(-2x+6)-36=0

We multiply parentheses ..

(+4x^2-12x-24x+72)-36=0

We get rid of parentheses

4x^2-12x-24x+72-36=0

We add all the numbers together, and all the variables

4x^2-36x+36=0

a = 4; b = -36; c = +36;
Δ = b2-4ac
Δ = -362-4·4·36
Δ = 720
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{720}=\sqrt{144*5}=\sqrt{144}*\sqrt{5}=12\sqrt{5}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-36)-12\sqrt{5}}{2*4}=\frac{36-12\sqrt{5}}{8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-36)+12\sqrt{5}}{2*4}=\frac{36+12\sqrt{5}}{8}
$