(4+y)(5y+9)=0

Solution for (4+y)(5y+9)=0 equation:

(4+y)(5y+9)=0

We add all the numbers together, and all the variables

(y+4)(5y+9)=0

We multiply parentheses ..

(+5y^2+9y+20y+36)=0

We get rid of parentheses

5y^2+9y+20y+36=0

We add all the numbers together, and all the variables

5y^2+29y+36=0

a = 5; b = 29; c = +36;
Δ = b2-4ac
Δ = 292-4·5·36
Δ = 121
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{121}=11$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(29)-11}{2*5}=\frac{-40}{10}
=-4
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(29)+11}{2*5}=\frac{-18}{10}
=-1+4/5
$