80.2 Chapter 2. Theory of first order differential equations. Excercise 2.6 at page 37

80.2.1 problem 1
80.2.2 problem 3
80.2.3 problem 4
80.2.4 problem 5
80.2.5 problem 6
80.2.6 problem 8
80.2.7 problem 9
80.2.8 problem 10
80.2.9 problem 12
80.2.10 problem 13
80.2.11 problem 14
80.2.12 problem 17
80.2.13 problem 19
80.2.14 problem 21
80.2.15 problem 22
80.2.16 problem 23
80.2.17 problem 24
80.2.18 problem 25
80.2.19 problem 26
80.2.20 problem 27
80.2.21 problem 28