Answers for Section 16.2

1.    A is 6 by 2. B is 2 by 3

3.   The matrix A does not have a main diagonal because it is not a square matrix. The entries of the main diagonal of B are 100 and 31.

5.    A is a zero matrix: D is an identity matrix.

7.    A + 2B =

9.    AB = [25 7 -6 0], BA does not exist.

11.   

13.   

15.    Multiply row 1 by 1/3.

17.    Infinite number of solutions

19.    This linear system is inconsistent:     x + 2y = 3

                                                              4x + 8y = 7