(X-12)(x-12)=64

Solution for (X-12)(x-12)=64 equation:

(X-12)(X-12)=64

We move all terms to the left:

(X-12)(X-12)-(64)=0

We multiply parentheses ..

(+X^2-12X-12X+144)-64=0

We get rid of parentheses

X^2-12X-12X+144-64=0

We add all the numbers together, and all the variables

X^2-24X+80=0

a = 1; b = -24; c = +80;
Δ = b2-4ac
Δ = -242-4·1·80
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-24)-16}{2*1}=\frac{8}{2}
=4
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-24)+16}{2*1}=\frac{40}{2}
=20
$