-7y(9y+6)=0

Solution for -7y(9y+6)=0 equation:

-7y(9y+6)=0

We multiply parentheses

-63y^2-42y=0

a = -63; b = -42; c = 0;
Δ = b2-4ac
Δ = -422-4·(-63)·0
Δ = 1764
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1764}=42$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-42)-42}{2*-63}=\frac{0}{-126}
=0
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-42)+42}{2*-63}=\frac{84}{-126}
=-2/3
$