4y(9y-4)=0

Solution for 4y(9y-4)=0 equation:

4y(9y-4)=0

We multiply parentheses

36y^2-16y=0

a = 36; b = -16; c = 0;
Δ = b2-4ac
Δ = -162-4·36·0
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-16)-16}{2*36}=\frac{0}{72}
=0
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-16)+16}{2*36}=\frac{32}{72}
=4/9
$