Find the order of the matrix product AB and the product BA w

Find the order of the matrix product AB and the product BA, whenever the products exist. A is 1 Times 4, B is 4 Times 1. AB is 1 Times 1, BA is nonexistent. AB is nonexistent, BA is 4 Times 4. AB is 1 Times 1, BA is 4 Times 4. AB is 4 Times 4, BA is 1 Times 1.

Solution

ANS: The order of product of 2 matrices is (m×n) where m = no. of rows in the first matrix and n = no. of columns in the 2nd matrix provided that they are consistent for multiplication.

Condition for consistency for multiplication is no. of columns in 1st matrix should be equal to no. of rows in 2nd matrix.

Now here AB = 1×1 & BA = 4×4 I.e. option c.