13.1 problem 1
13.2 problem 2
13.3 problem 3
13.4 problem 4
13.5 problem 5
13.6 problem 6
13.7 problem 7
13.8 problem 8
13.9 problem 9
13.10 problem 10
13.11 problem 11
13.12 problem 12
13.13 problem 13
13.14 problem 14
13.15 problem 15
13.16 problem 19
13.17 problem 20
13.18 problem 21
13.19 problem 22
13.20 problem 23
13.21 problem 24
13.22 problem 25
13.23 problem 26
13.24 problem 27
13.25 problem 28
13.26 problem 29
13.27 problem 31(a)
13.28 problem 31(b)
13.29 problem 31(c)
13.30 problem 31(d)
13.31 problem 31(e)
13.32 problem 32
13.33 problem 33
13.34 problem 34
13.35 problem 35
13.36 problem 36
13.37 problem 37
13.38 problem 38
13.39 problem 39 (a)
13.40 problem 39 (b)
13.41 problem 40
13.42 problem 41
13.43 problem 42
13.44 problem 43
13.45 problem 44
13.46 problem 45
13.47 problem 46
13.48 problem 47
13.49 problem 48
13.50 problem 49