(5y-1)(8+y)=0

Solution for (5y-1)(8+y)=0 equation:

(5y-1)(8+y)=0

We add all the numbers together, and all the variables

(5y-1)(y+8)=0

We multiply parentheses ..

(+5y^2+40y-1y-8)=0

We get rid of parentheses

5y^2+40y-1y-8=0

We add all the numbers together, and all the variables

5y^2+39y-8=0

a = 5; b = 39; c = -8;
Δ = b2-4ac
Δ = 392-4·5·(-8)
Δ = 1681
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1681}=41$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(39)-41}{2*5}=\frac{-80}{10}
=-8
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(39)+41}{2*5}=\frac{2}{10}
=1/5
$