Page 151 - Schaum's Outline of Differential Equations

134 MATRICES [CHAP. 15

2
15.4. Find (2A - B) for the matrices given in Problem 15.1.

and

15.5. Find AB and BA for

Since A has three columns and B has two rows, the product AB is not defined. But

15.6. Find AB and AC if

Note that for these matrices AB = AC and yet B ^ C. Therefore, the cancellation law is not valid for matrix
multiplication.