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

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

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

We add all the numbers together, and all the variables

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

We multiply parentheses ..

(+3y^2+9y+7y+21)=0

We get rid of parentheses

3y^2+9y+7y+21=0

We add all the numbers together, and all the variables

3y^2+16y+21=0

a = 3; b = 16; c = +21;
Δ = b2-4ac
Δ = 162-4·3·21
Δ = 4
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4}=2$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(16)-2}{2*3}=\frac{-18}{6}
=-3
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(16)+2}{2*3}=\frac{-14}{6}
=-2+1/3
$