(7y+9)(9y+11)=0

Solution for (7y+9)(9y+11)=0 equation:

(7y+9)(9y+11)=0

We multiply parentheses ..

(+63y^2+77y+81y+99)=0

We get rid of parentheses

63y^2+77y+81y+99=0

We add all the numbers together, and all the variables

63y^2+158y+99=0

a = 63; b = 158; c = +99;
Δ = b2-4ac
Δ = 1582-4·63·99
Δ = 16
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{16}=4$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(158)-4}{2*63}=\frac{-162}{126}
=-1+2/7
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(158)+4}{2*63}=\frac{-154}{126}
=-1+2/9
$