Mathematics

Problem

Which of the following statements about the multiplication of two square matrices

A

and

B

of the same order is correct? a)

AB \text{ need not be equal to } BA \text{ in general}

AB = BA \text{ for every pair of square matrices of the same order}

AB \text{ is defined only when both } A \text{ and } B \text{ are diagonal matrices}

\text{If } A \text{ and } B \text{ are non-singular, then } AB = BA