88.11 Chapter 2. Differential equations of first order. Exercise at page 54

88.11.1 problem 1
88.11.2 problem 1
88.11.3 problem 3
88.11.4 problem 4
88.11.5 problem 6
88.11.6 problem 7
88.11.7 problem 8
88.11.8 problem 9
88.11.9 problem 10