From 3.3: all odd problems Problem 11 and above except the ones on matrices and except 15,17,19 BONUS type problems: Starred odd problems in the supplementary exercises for Chapter 3.
From 4.1, 4.2, 4.3: All Odd "prove that" or "show that" problems, i.e., problems that need an argument. Do the others if you need to be sure you got the definitions/concepts from the chapter.