31 Chapter 3 (Systems of differential equations). Section 23.2 The method of undetermined coefficients. Exercises page 239

31.1 problem 815
31.2 problem 816
31.3 problem 817
31.4 problem 818
31.5 problem 819
31.6 problem 820
31.7 problem 821
31.8 problem 822
31.9 problem 823
31.10 problem 824