x^2+2x=39999

Solution for x^2+2x=39999 equation:

x^2+2x=39999

We move all terms to the left:

x^2+2x-(39999)=0

a = 1; b = 2; c = -39999;
Δ = b2-4ac
Δ = 22-4·1·(-39999)
Δ = 160000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{160000}=400$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2)-400}{2*1}=\frac{-402}{2}
=-201
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+400}{2*1}=\frac{398}{2}
=199
$