Part 2a: Systems of Linear Equations
page 63 (section 2.3):   # 3, 5, 9, 10, 12, 19, 26.
    Comments:   #19:  Which rows are exchanged when P and Q left-multiply a matrix? 
         Thinking about this question may help with finding a row exchange matrix M.

Part 2b: Rules for Matrix Operations
page 75 (section 2.4):   # 6, 9, 16, 18, 23, 32, 34.
    Comments:   #23:  If your answer is not "simple" enough in part a) you 
                      may have trouble with b).  Use only zeros and ones for a).
                      Then interpret it as a row operation.  It is copying zeros.  
                      Now try b) using that idea.  You will need 3 rows.

Part 2c: Matrix Inverses
page 89 (section 2.5):   # 2, 7, 8.
    Comments:  #7 and 8: Definitions:  Invertible means that a matrix has an inverse.  
                             That is, it is not singular.
               #7: It might be easier to do parts b) and c) before doing part a).

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?