3.2-3.2.1, due Oct 16

1) I had the most trouble understanding the proof if Lemma 3.2.1. I feel like the left out some of their justification for their steps.

2) I've done some problems having to do with Pythagorean triples, so when I read some of the thrms and things they had to say about them, I noticed that I already knew a lot of what they had to say.