3y(7y+1)=0

Solution for 3y(7y+1)=0 equation:

3y(7y+1)=0

We multiply parentheses

21y^2+3y=0

a = 21; b = 3; c = 0;
Δ = b2-4ac
Δ = 32-4·21·0
Δ = 9
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9}=3$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(3)-3}{2*21}=\frac{-6}{42}
=-1/7
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3)+3}{2*21}=\frac{0}{42}
=0
$