7.9 Section 2.2.2, Equal roots, reduction of order. Page 147

7.9.1 problem 1
7.9.2 problem 2
7.9.3 problem 3
7.9.4 problem 4
7.9.5 problem 6
7.9.6 problem 7
7.9.7 problem 10
7.9.8 problem 11
7.9.9 problem 12
7.9.10 problem 13
7.9.11 problem 14
7.9.12 problem 15
7.9.13 problem 16
7.9.14 problem 19
7.9.15 problem 20