0=2500-400x+8x^2

Solution for 0=2500-400x+8x^2 equation:

0=2500-400x+8x^2

We move all terms to the left:

0-(2500-400x+8x^2)=0

We add all the numbers together, and all the variables

-(2500-400x+8x^2)=0

We get rid of parentheses

-8x^2+400x-2500=0

a = -8; b = 400; c = -2500;
Δ = b2-4ac
Δ = 4002-4·(-8)·(-2500)
Δ = 80000
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:

$\sqrt{\Delta}=\sqrt{80000}=\sqrt{40000*2}=\sqrt{40000}*\sqrt{2}=200\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(400)-200\sqrt{2}}{2*-8}=\frac{-400-200\sqrt{2}}{-16}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(400)+200\sqrt{2}}{2*-8}=\frac{-400+200\sqrt{2}}{-16}
$