2600=x^2+2x

Solution for 2600=x^2+2x equation:

2600=x^2+2x

We move all terms to the left:

2600-(x^2+2x)=0

We get rid of parentheses

-x^2-2x+2600=0

We add all the numbers together, and all the variables

-1x^2-2x+2600=0

a = -1; b = -2; c = +2600;
Δ = b2-4ac
Δ = -22-4·(-1)·2600
Δ = 10404
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{10404}=102$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-102}{2*-1}=\frac{-100}{-2}
=+50
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+102}{2*-1}=\frac{104}{-2}
=-52
$