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If A and B are symmetric matrices, prove that AB − BA is a skew-symmetric matrix. |
Answer» Here, A and B are symmetric matrices, then A′ = A and B′ = B Now, (AB − BA)′ = (AB)′ − (BA)′ (∵(A − B)′ = A′ − B′ and (AB)′ = (B′A′) = B ′A′ − A′B′ = BA − AB (∵ B′ = B and A′ = A) = −(AB − BA) ⇒(AB − BA)′ = −(AB − BA) Thus, (AB − BA) is a skew-symmetric matrix. |
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