If A is an 2 × 4 matrix and B is an 4 × 9 matrix, then:
A) BA is defined and has order 2 × 9.
B) BA is defined and has order 9 × 2.
C) AB is defined and has order 9 × 2.
D) AB is defined and has order 2 × 9.
E) Neither AB nor BA is defined.

Question

Quizplus · Accepted Answer

Matrix multiplication is defined when the number of columns in the first matrix equals the number of rows in the second matrix. Here, AB is defined because A is 2 × 4 and B is 4 × 9, resulting in a 2 × 9 matrix.

If a Is an 2 × 4 Matrix and B