(-9y-1)(-2y+5)=0

Solution for (-9y-1)(-2y+5)=0 equation:

(-9y-1)(-2y+5)=0

We multiply parentheses ..

(+18y^2-45y+2y-5)=0

We get rid of parentheses

18y^2-45y+2y-5=0

We add all the numbers together, and all the variables

18y^2-43y-5=0

a = 18; b = -43; c = -5;
Δ = b2-4ac
Δ = -432-4·18·(-5)
Δ = 2209
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2209}=47$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-43)-47}{2*18}=\frac{-4}{36}
=-1/9
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-43)+47}{2*18}=\frac{90}{36}
=2+1/2
$