x(200-4x)=0

Solution for x(200-4x)=0 equation:

x(200-4x)=0

We add all the numbers together, and all the variables

x(-4x+200)=0

We multiply parentheses

-4x^2+200x=0

a = -4; b = 200; c = 0;
Δ = b2-4ac
Δ = 2002-4·(-4)·0
Δ = 40000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{40000}=200$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(200)-200}{2*-4}=\frac{-400}{-8}
=+50
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(200)+200}{2*-4}=\frac{0}{-8}
=0
$