X^2+40x-216=0

Solution for X^2+40x-216=0 equation:

X^2+40X-216=0

a = 1; b = 40; c = -216;
Δ = b2-4ac
Δ = 402-4·1·(-216)
Δ = 2464
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{2464}=\sqrt{16*154}=\sqrt{16}*\sqrt{154}=4\sqrt{154}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(40)-4\sqrt{154}}{2*1}=\frac{-40-4\sqrt{154}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(40)+4\sqrt{154}}{2*1}=\frac{-40+4\sqrt{154}}{2}
$