X^2+2*x=870

Solution for X^2+2*x=870 equation:

X^2+2X=870

We move all terms to the left:

X^2+2X-(870)=0

a = 1; b = 2; c = -870;
Δ = b2-4ac
Δ = 22-4·1·(-870)
Δ = 3484
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:

$\sqrt{\Delta}=\sqrt{3484}=\sqrt{4*871}=\sqrt{4}*\sqrt{871}=2\sqrt{871}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2)-2\sqrt{871}}{2*1}=\frac{-2-2\sqrt{871}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+2\sqrt{871}}{2*1}=\frac{-2+2\sqrt{871}}{2}
$