Part 6a: Null Space, Column Space
page 140 (section 3.2):   # 15, 17, 18, 22, 26.
    Comments:  # 26: Write the condition for a vector n to be in N(A).  
       Then for n to be in C(A).  Now use #23a from section 2.4.

Part 6b: Rank and rref (row reduced echelon form)
page 151 (section 3.3):   # 2, 3, 8, 9, 10, 20(1st sentence only).
    Comments:  # 20: Use the results from 17 and 18.  Don't bother with
       the second sentence.  The 1st gives the result stated in the 3rd sentence.

Part 6c: Complete Solution to Ax=b
page 163 (section 3.4):   # 15, 17, 19, 21, 22, 23, 25, 29, 31, 33.
    Comment:  # 22: note that B is a vector like b--they just needed another letter.
              # 25: answers in back--so explain why the answer is true.
         There are lots of problems to do here.  But each should not take too long.     

1. What idea do you believe is the most important in each part and why?
2. What troubles did you have with the assignment, if any?