4 Section 2.5. Page 88

4.1 problem 1
4.2 problem 3
4.3 problem 4
4.4 problem 5
4.5 problem 6
4.6 problem 7
4.7 problem 9
4.8 problem 10
4.9 problem 11
4.10 problem 12
4.11 problem 13