5y(2y-20)=0

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

5y(2y-20)=0

We multiply parentheses

10y^2-100y=0

a = 10; b = -100; c = 0;
Δ = b2-4ac
Δ = -1002-4·10·0
Δ = 10000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{10000}=100$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-100)-100}{2*10}=\frac{0}{20}
=0
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-100)+100}{2*10}=\frac{200}{20}
=10
$