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)(AB−BA)′=−(AB−BA)
Hence, AB - BA is a skew-symmetric matrix.