Midterm 1 Q&A
1 General math
1.1 When simplifying a sum, how do you know when to reindex?
Answer
Reindexing a sum is analogous to applying a \(u\)-substitution to an integral, so a lot of your intuitions about that carry over. But to be concrete, let me draw your attention to some examples from the course where a reindex happened:
- Problem Set 0 #2;
- Prob
In each case, the form of the original expression tips you off about
Do whatever you have to do to muscle it into that form.
2 Set theory and probability spaces
2.1 How do you start proofs?
Answer
3 Counting
3.1 How do you tell if order matters or not?
Answer
3.2 Under what circumstances do the “ordered” and the “unordered” answers agree?
Answer
We saw this on the Spotify.
3.3 I am confused about “stars and bars.”
Answer