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

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

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

We multiply parentheses ..

(+40n^2-40n+8n-8)=0

We get rid of parentheses

40n^2-40n+8n-8=0

We add all the numbers together, and all the variables

40n^2-32n-8=0

a = 40; b = -32; c = -8;
Δ = b2-4ac
Δ = -322-4·40·(-8)
Δ = 2304
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2304}=48$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-32)-48}{2*40}=\frac{-16}{80}
=-1/5
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-32)+48}{2*40}=\frac{80}{80}
=1
$