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Ques. The product of matrices (PQ)-1P is

(a)    P-1                                 (b)     Q-1

(c)    P-1Q-1P                           (d)    PQP-1

Ans. \((Q^-1P)^-1P=Q^-1(P^-1P)\)
\(=Q^-1I=Q^-1\)