X2+x-216=0

Solution for X2+x-216=0 equation:

X2+X-216=0

We add all the numbers together, and all the variables

X^2+X-216=0

a = 1; b = 1; c = -216;
Δ = b2-4ac
Δ = 12-4·1·(-216)
Δ = 865
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{865}}{2*1}=\frac{-1-\sqrt{865}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{865}}{2*1}=\frac{-1+\sqrt{865}}{2}
$