Chapter 2, section 2.1 (Exact diﬀerential equations and integrating factors). Exercises page 37

3.1 problem 1
3.2 problem 2
3.3 problem 3
3.4 problem 4
3.5 problem 5
3.6 problem 7
3.7 problem 8
3.8 problem 9
3.9 problem 10
3.10 problem 11
3.11 problem 12
3.12 problem 13
3.13 problem 14
3.14 problem 15
3.15 problem 16
3.16 problem 21
3.17 problem 22
3.18 problem 24