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

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

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

We multiply parentheses ..

(+3y^2-24y+7y-56)=0

We get rid of parentheses

3y^2-24y+7y-56=0

We add all the numbers together, and all the variables

3y^2-17y-56=0

a = 3; b = -17; c = -56;
Δ = b2-4ac
Δ = -172-4·3·(-56)
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{-(-17)-31}{2*3}=\frac{-14}{6}
=-2+1/3
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-17)+31}{2*3}=\frac{48}{6}
=8
$