3.5: 2 (answer: not a subspace), 5, 17, 19, 27, 49
3.6: 1, 9, 15, 17, 21
4.1: 5, 7, 9, 15, 17, 23 (hw), 25
4.2: 1, 7, 13, 15, 26 (answer: 0), 27

(hw) — the problem is from the homework