19 Chapter 5. Applications of Higher Order Equations. Exercises 5.1, page 232

19.1 problem 1
19.2 problem 2
19.3 problem 3
19.4 problem 4
19.5 problem 5
19.6 problem 6
19.7 problem 7
19.8 problem 8
19.9 problem 9
19.10 problem 10