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

Solution for (8+y)(5y+9)=0 equation:

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

We add all the numbers together, and all the variables

(y+8)(5y+9)=0

We multiply parentheses ..

(+5y^2+9y+40y+72)=0

We get rid of parentheses

5y^2+9y+40y+72=0

We add all the numbers together, and all the variables

5y^2+49y+72=0

a = 5; b = 49; c = +72;
Δ = b2-4ac
Δ = 492-4·5·72
Δ = 961
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{961}=31$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(49)-31}{2*5}=\frac{-80}{10}
=-8
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(49)+31}{2*5}=\frac{-18}{10}
=-1+4/5
$