Prove Theorem 8.1(d) by establishing each of the following results: (a) If A is an m x...

Prove Theorem 8.1(d) by establishing each of the following results:

(a) If A is an m x n matrix and 0 is the n x p zero matrix, then A 0 is the m x p zero matrix.

(b) If 0 is the m x n zero matrix and B is any n x p matrix, then OB is the m x p zero matrix.