Learning Goal: I’m working on a number theory question and need the explanation and answer to help me learn.
Exercises 8:A. 3, 6, 12, 15, 17, 22. D. 2, 7. E. 12, 13 (see below regarding 8E).
Exercises 9: A. 2. B. 2, 3.
Some extra instructions for the questions in 8E: as with the problems in Exercises 7F on the last assignment, these are incorrect “proofs� and you are asked to identify all the mistakes. You should consider each line separately, and ask yourself if it is correct assuming that the previous lines were correct (even if you already figured out that one or more of them weren’t correct). In particular, even if you find a mistake on line number n, it does not automatically mean that every later line that uses line n is necessarily “incorrect� in this sense.