How does step 1 convert to step 2? We don't know what n is so I think step 2 is just making assumptions

Module 1 Week 1 Day 1 Your Turn Part 1 MiniQuestion
How does step 1 convert to step 2? We don't know what n is so I think step 2 is just making assumptions

@thebladedancer The second step looks quite different from the first step! It's because for the first two fractions, we have multiplied the top and bottom by a factor.
For the first fraction, we have multiplied the top and bottom by \( n + 1.\)
\(\frac{1}{\textcolor{red}{n}} = \frac{n + 1}{\textcolor{red}{n} (n + 1) } \)
For the second fraction, we have multiplied the top and bottom by \(n.\)
\(\frac{1}{\textcolor{red}{n+1}} = \frac{n}{\textcolor{red}{(n +1)} n } \)
For the third fraction, we've done something different: we have factored the bottom. (Factor just means to write as a product of two terms, like \( 12 = 3 \times 4.\) )
\(  \frac{1}{n^2 + n} =  \frac{1}{n(n+1)} \)
Why are we trying to do this? To make the bottoms of the fractions all equal to \( n(n+1).\) Then we can add the fractions together very easily, and luckily we have some terms cancel out, so we get \(0\) on the top, which is a little fortunate!
\( \frac{n + 1  n  1}{n(n+1)} \)
\( = \frac{0}{n(n+1)} = \boxed{0}.\)