400,000=-2x^2+2000x

Solution for 400,000=-2x^2+2000x equation:

400.000=-2x^2+2000x

We move all terms to the left:

400.000-(-2x^2+2000x)=0

We add all the numbers together, and all the variables

-(-2x^2+2000x)+400=0

We get rid of parentheses

2x^2-2000x+400=0

a = 2; b = -2000; c = +400;
Δ = b2-4ac
Δ = -20002-4·2·400
Δ = 3996800
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:

$\sqrt{\Delta}=\sqrt{3996800}=\sqrt{1600*2498}=\sqrt{1600}*\sqrt{2498}=40\sqrt{2498}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2000)-40\sqrt{2498}}{2*2}=\frac{2000-40\sqrt{2498}}{4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2000)+40\sqrt{2498}}{2*2}=\frac{2000+40\sqrt{2498}}{4}
$