-9y(2y-7)=0

Solution for -9y(2y-7)=0 equation:

-9y(2y-7)=0

We multiply parentheses

-18y^2+63y=0

a = -18; b = 63; c = 0;
Δ = b2-4ac
Δ = 632-4·(-18)·0
Δ = 3969
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3969}=63$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(63)-63}{2*-18}=\frac{-126}{-36}
=3+1/2
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(63)+63}{2*-18}=\frac{0}{-36}
=0
$