5000=-5x^2+400x

Solution for 5000=-5x^2+400x equation:

5000=-5x^2+400x

We move all terms to the left:

5000-(-5x^2+400x)=0

We get rid of parentheses

5x^2-400x+5000=0

a = 5; b = -400; c = +5000;
Δ = b2-4ac
Δ = -4002-4·5·5000
Δ = 60000
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:

$\sqrt{\Delta}=\sqrt{60000}=\sqrt{10000*6}=\sqrt{10000}*\sqrt{6}=100\sqrt{6}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-400)-100\sqrt{6}}{2*5}=\frac{400-100\sqrt{6}}{10}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-400)+100\sqrt{6}}{2*5}=\frac{400+100\sqrt{6}}{10}
$