64.9 Chapter 4, Section 4.1. Basic theory of linear differential equations. Exercises page 124

64.9.1 problem 1
64.9.2 problem 2
64.9.3 problem 3
64.9.4 problem 4
64.9.5 problem 5
64.9.6 problem 6
64.9.7 problem 8
64.9.8 problem 9