144=(36-x)*x

Solution for 144=(36-x)*x equation:

144=(36-x)*x

We move all terms to the left:

144-((36-x)*x)=0

We add all the numbers together, and all the variables

-((-1x+36)*x)+144=0


We calculate terms in parentheses: -((-1x+36)*x), so:

(-1x+36)*x

We multiply parentheses

-1x^2+36x

Back to the equation:

-(-1x^2+36x)


We get rid of parentheses

1x^2-36x+144=0

We add all the numbers together, and all the variables

x^2-36x+144=0

a = 1; b = -36; c = +144;
Δ = b2-4ac
Δ = -362-4·1·144
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*1}=\frac{36-12\sqrt{5}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-36)+12\sqrt{5}}{2*1}=\frac{36+12\sqrt{5}}{2}
$