Question

If A is 3 × 4 matrix and B is a matrix such that A'B and BA' are both defined. Then, B is of the type 

Options

• 3 × 4

• 3 × 3

• 4 × 4 

• 4 × 3

Answer 1

3 × 4 

The order of A is 3x  4. So, the order of A' is 4x  3 

Now, both 

`A’B` and `BA’` are defined. So, the number of columns in A' should be equal to the number of rows in B for A'B.
Also, the number of columns in B should be equal to number of rows in A' for BA'.

Hence, the order of matrix B is 3 X   4