If B is a symmetric matrix, write whether the matrix AB AT is symmetric or skew-symmetric.

B is a symmetric matrix, then

BT = B …(i)


Consider


(ABAT)T = (AT)T BT AT


[ (AB)T = BTAT]


(ABAT)T = ABTAT [ (AT)T = A]


(ABAT)T = A(B)AT [from (i)]


(ABAT)T = ABAT


ABAT is a symmetric matrix


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