X^2+8x-408=0

Solution for X^2+8x-408=0 equation:

X^2+8X-408=0

a = 1; b = 8; c = -408;
Δ = b2-4ac
Δ = 82-4·1·(-408)
Δ = 1696
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:

$\sqrt{\Delta}=\sqrt{1696}=\sqrt{16*106}=\sqrt{16}*\sqrt{106}=4\sqrt{106}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(8)-4\sqrt{106}}{2*1}=\frac{-8-4\sqrt{106}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8)+4\sqrt{106}}{2*1}=\frac{-8+4\sqrt{106}}{2}
$