Question

If A and B are square matrices of order 2 such that det(AB) = det(BA), then which one of the following is correct?
1. A must be a unit matrix.
2. B must be a unit matrix.
3. Both A and B must be unit matrices.
4. A and B need not be unit matrices.

Answer 1

Correct Answer - Option 3 : Both A and B must be unit matrices.

Explanation:

If A and B are square matrices of order 2 such that det(AB) = det(BA)

Only possible when A and B must be the Unit Matrix.