23.4 Chapter 6. Linear systems. Exercises at page 110

23.4.1 problem 8(a)
23.4.2 problem 8(b)
23.4.3 problem 8(c)
23.4.4 problem 8(d)
23.4.5 problem 8(e)
23.4.6 problem 8(f)
23.4.7 problem 8(g)
23.4.8 problem 9
23.4.9 problem 10
23.4.10 problem 11(a)
23.4.11 problem 11(b)
23.4.12 problem 11(c)