21 Chapter 30. Piecewise-defined functions and periodic functions. Additional Exercises. page 553

21.1 problem 30.6 (a)
21.2 problem 30.6 (b)
21.3 problem 30.6 (c)
21.4 problem 30.6 (d)
21.5 problem 30.6 (e)
21.6 problem 30.10 (a)
21.7 problem 30.10 (b)
21.8 problem 30.10 (c)