Due on Wednesday, October 25, at the beginning of the class
3.5, 3.11, 3.12, 3.15 (turn in)
3.4, 3.6, 3.10, 3.13 (optional, do NOT turn in)
SOME TIPS ON WRITING PROOFS
Use complete sentences as much as possible;
it's OK to use mathematical shorthand,
but be careful, especially with the quantifiers "there exists", "for all"
(don't omit them); inidicate where your points are, e.g. "for all x in R"
Explain what you're doing.
A good model for a proof is this: first you should say what
you are going to do, then you should do it, and then you
should say what you did.