Section 5.5 Ex. 1-4,6,7,9,11,15,20.
 Note: the exercises from 5.5 are difficult. So I handed out the answers
 of some of these homework questions together with the answers of test 3
 that I handed out.

Section 5.6 Ex. 1-3, 7-11, 15, 16.
Section 6.1 Ex. 1-4, 5-7, 10, 11, 16.