X=x^2-6x-20

Solution for X=x^2-6x-20 equation:

X=X^2-6X-20

We move all terms to the left:

X-(X^2-6X-20)=0

We get rid of parentheses

-X^2+X+6X+20=0

We add all the numbers together, and all the variables

-1X^2+7X+20=0

a = -1; b = 7; c = +20;
Δ = b2-4ac
Δ = 72-4·(-1)·20
Δ = 129
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{-(7)-\sqrt{129}}{2*-1}=\frac{-7-\sqrt{129}}{-2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(7)+\sqrt{129}}{2*-1}=\frac{-7+\sqrt{129}}{-2}
$