(7+y)(3y+8)=0

Solution for (7+y)(3y+8)=0 equation:

(7+y)(3y+8)=0

We add all the numbers together, and all the variables

(y+7)(3y+8)=0

We multiply parentheses ..

(+3y^2+8y+21y+56)=0

We get rid of parentheses

3y^2+8y+21y+56=0

We add all the numbers together, and all the variables

3y^2+29y+56=0

a = 3; b = 29; c = +56;
Δ = b2-4ac
Δ = 292-4·3·56
Δ = 169
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{169}=13$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(29)-13}{2*3}=\frac{-42}{6}
=-7
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(29)+13}{2*3}=\frac{-16}{6}
=-2+2/3
$