1 Chapter 4.1, Higher order linear differential equations. General theory. page 173

 1.1 problem 1
 1.2 problem 2
 1.3 problem 8
 1.4 problem 9
 1.5 problem 10
 1.6 problem 11
 1.7 problem 16
 1.8 problem 17
 1.9 problem 20
 1.10 problem 21