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

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

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

We add all the numbers together, and all the variables

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

We multiply parentheses ..

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

We get rid of parentheses

-5y^2+5y-9y+9=0

We add all the numbers together, and all the variables

-5y^2-4y+9=0

a = -5; b = -4; c = +9;
Δ = b2-4ac
Δ = -42-4·(-5)·9
Δ = 196
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{196}=14$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4)-14}{2*-5}=\frac{-10}{-10}
=1
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+14}{2*-5}=\frac{18}{-10}
=-1+4/5
$