If A and B are symmetric matrices, then AB – BA is a
symmetric matrix
skew-symmetric matrix
diagonal matrix
null matrix
We are given A′=A,B′=B
Now (AB−BA)′=(AB)′−(BA)′=B′A′−A′B′
=BA−AB=−(AB−BA)
i.e. (AB−BA)′=−(AB−BA)
Hence, AB-BA is a skew-symmetric matrix.