X2+x-20=5

Solution for X2+x-20=5 equation:

X2+X-20=5

We move all terms to the left:

X2+X-20-(5)=0

We add all the numbers together, and all the variables

X^2+X-25=0

a = 1; b = 1; c = -25;
Δ = b2-4ac
Δ = 12-4·1·(-25)
Δ = 101
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{-(1)-\sqrt{101}}{2*1}=\frac{-1-\sqrt{101}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{101}}{2*1}=\frac{-1+\sqrt{101}}{2}
$