4y(2y-10)=0

Solution for 4y(2y-10)=0 equation:

4y(2y-10)=0

We multiply parentheses

8y^2-40y=0

a = 8; b = -40; c = 0;
Δ = b2-4ac
Δ = -402-4·8·0
Δ = 1600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1600}=40$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-40)-40}{2*8}=\frac{0}{16}
=0
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-40)+40}{2*8}=\frac{80}{16}
=5
$