10 Section 2.4, The method of variation of parameters. Page 154

 10.1 problem 1
 10.2 problem 2
 10.3 problem 3
 10.4 problem 4
 10.5 problem 5
 10.6 problem 6
 10.7 problem 7
 10.8 problem 8
 10.9 problem 11
 10.10 problem 12