(5y+8)(7+y)=0

Solution for (5y+8)(7+y)=0 equation:

(5y+8)(7+y)=0

We add all the numbers together, and all the variables

(5y+8)(y+7)=0

We multiply parentheses ..

(+5y^2+35y+8y+56)=0

We get rid of parentheses

5y^2+35y+8y+56=0

We add all the numbers together, and all the variables

5y^2+43y+56=0

a = 5; b = 43; c = +56;
Δ = b2-4ac
Δ = 432-4·5·56
Δ = 729
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{729}=27$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(43)-27}{2*5}=\frac{-70}{10}
=-7
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(43)+27}{2*5}=\frac{-16}{10}
=-1+3/5
$