2000=10x+x^2

Solution for 2000=10x+x^2 equation:

2000=10x+x^2

We move all terms to the left:

2000-(10x+x^2)=0

We get rid of parentheses

-x^2-10x+2000=0

We add all the numbers together, and all the variables

-1x^2-10x+2000=0

a = -1; b = -10; c = +2000;
Δ = b2-4ac
Δ = -102-4·(-1)·2000
Δ = 8100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{8100}=90$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-10)-90}{2*-1}=\frac{-80}{-2}
=+40
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+90}{2*-1}=\frac{100}{-2}
=-50
$