84.20 Chapter 12. Second order linear homogeneous differential equations with constant coefficients. Supplementary problems

84.20.1 problem 12.9
84.20.2 problem 12.10
84.20.3 problem 12.11
84.20.4 problem 12.12
84.20.5 problem 12.13
84.20.6 problem 12.14
84.20.7 problem 12.15
84.20.8 problem 12.16
84.20.9 problem 12.17
84.20.10 problem 12.18