11 Chapter 8, Linear differential equations of order n. Section 8.9, Reduction of Order. page 572

 11.1 problem Problem 1
 11.2 problem Problem 2
 11.3 problem Problem 3
 11.4 problem Problem 4
 11.5 problem Problem 5
 11.6 problem Problem 6
 11.7 problem Problem 10
 11.8 problem Problem 11
 11.9 problem Problem 12
 11.10 problem Problem 13
 11.11 problem Problem 14
 11.12 problem Problem 15