(X)=x2-8x-20

Solution for (X)=x2-8x-20 equation:

(X)=X2-8X-20

We move all terms to the left:

(X)-(X2-8X-20)=0

We add all the numbers together, and all the variables

-(+X^2-8X-20)+X=0

We get rid of parentheses

-X^2+8X+X+20=0

We add all the numbers together, and all the variables

-1X^2+9X+20=0

a = -1; b = 9; c = +20;
Δ = b2-4ac
Δ = 92-4·(-1)·20
Δ = 161
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{-(9)-\sqrt{161}}{2*-1}=\frac{-9-\sqrt{161}}{-2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+\sqrt{161}}{2*-1}=\frac{-9+\sqrt{161}}{-2}
$