19 Chapter 4, Linear Systems. Exercises page 202

19.1 problem 1(a)
19.2 problem 1(b)
19.3 problem 1(c)
19.4 problem 1(d)
19.5 problem 1(e)
19.6 problem 1(f)
19.7 problem 3(a)
19.8 problem 3(b)