The sizes of two matrices are given. Find the size of the product AB and the size of the product BA, if the given product can be calculated. A is 1 × 3; B is 3 × 1.

Question

do not understand algebra please help

Answer 1

The product of an m x n matrix and an n x p matrix, in that order left to right, must be an m x p matrix.

A is 1 x 3

B is 3 x 1

AB is 1 x 1

Similarly,

BA is 3 x 3.