x^2-20x=5-18

Solution for x^2-20x=5-18 equation:

x^2-20x=5-18

We move all terms to the left:

x^2-20x-(5-18)=0

We add all the numbers together, and all the variables

x^2-20x-(-13)=0

We add all the numbers together, and all the variables

x^2-20x+13=0

a = 1; b = -20; c = +13;
Δ = b2-4ac
Δ = -202-4·1·13
Δ = 348
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:

$\sqrt{\Delta}=\sqrt{348}=\sqrt{4*87}=\sqrt{4}*\sqrt{87}=2\sqrt{87}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-2\sqrt{87}}{2*1}=\frac{20-2\sqrt{87}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+2\sqrt{87}}{2*1}=\frac{20+2\sqrt{87}}{2}
$