X^2+x-1=13

Solution for X^2+x-1=13 equation:

X^2+X-1=13

We move all terms to the left:

X^2+X-1-(13)=0

We add all the numbers together, and all the variables

X^2+X-14=0

a = 1; b = 1; c = -14;
Δ = b2-4ac
Δ = 12-4·1·(-14)
Δ = 57
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{57}}{2*1}=\frac{-1-\sqrt{57}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{57}}{2*1}=\frac{-1+\sqrt{57}}{2}
$