x^2-10x-20=0x

Solution for x^2-10x-20=0x equation:

x^2-10x-20=0x

We move all terms to the left:

x^2-10x-20-(0x)=0

We add all the numbers together, and all the variables

x^2-11x-20=0

a = 1; b = -11; c = -20;
Δ = b2-4ac
Δ = -112-4·1·(-20)
Δ = 201
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-11)-\sqrt{201}}{2*1}=\frac{11-\sqrt{201}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-11)+\sqrt{201}}{2*1}=\frac{11+\sqrt{201}}{2}
$