X^2+4x-640=0

Solution for X^2+4x-640=0 equation:

X^2+4X-640=0

a = 1; b = 4; c = -640;
Δ = b2-4ac
Δ = 42-4·1·(-640)
Δ = 2576
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:

$\sqrt{\Delta}=\sqrt{2576}=\sqrt{16*161}=\sqrt{16}*\sqrt{161}=4\sqrt{161}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-4\sqrt{161}}{2*1}=\frac{-4-4\sqrt{161}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+4\sqrt{161}}{2*1}=\frac{-4+4\sqrt{161}}{2}
$