5y(7y-4)=0

Solution for 5y(7y-4)=0 equation:

5y(7y-4)=0

We multiply parentheses

35y^2-20y=0

a = 35; b = -20; c = 0;
Δ = b2-4ac
Δ = -202-4·35·0
Δ = 400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{400}=20$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-20}{2*35}=\frac{0}{70}
=0
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+20}{2*35}=\frac{40}{70}
=4/7
$