20x(5-2x)=0

Solution for 20x(5-2x)=0 equation:

20x(5-2x)=0

We add all the numbers together, and all the variables

20x(-2x+5)=0

We multiply parentheses

-40x^2+100x=0

a = -40; b = 100; c = 0;
Δ = b2-4ac
Δ = 1002-4·(-40)·0
Δ = 10000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{10000}=100$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(100)-100}{2*-40}=\frac{-200}{-80}
=2+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(100)+100}{2*-40}=\frac{0}{-80}
=0
$