(5y+1)(y=8)

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

(5y+1)(y=8)

We move all terms to the left:

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

We multiply parentheses ..

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

We get rid of parentheses

5y^2-40y+y-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{-2}{10}
=-1/5
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-39)+41}{2*5}=\frac{80}{10}
=8
$