(X-20)(x-20)=14

Solution for (X-20)(x-20)=14 equation:

(X-20)(X-20)=14

We move all terms to the left:

(X-20)(X-20)-(14)=0

We multiply parentheses ..

(+X^2-20X-20X+400)-14=0

We get rid of parentheses

X^2-20X-20X+400-14=0

We add all the numbers together, and all the variables

X^2-40X+386=0

a = 1; b = -40; c = +386;
Δ = b2-4ac
Δ = -402-4·1·386
Δ = 56
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:

$\sqrt{\Delta}=\sqrt{56}=\sqrt{4*14}=\sqrt{4}*\sqrt{14}=2\sqrt{14}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-40)-2\sqrt{14}}{2*1}=\frac{40-2\sqrt{14}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-40)+2\sqrt{14}}{2*1}=\frac{40+2\sqrt{14}}{2}
$