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Which of the following statements are correct?

A. If PP and QQ are square matrices of same order, then (PQT−QPT)(PQ^T-QP^T) is a skew symmetric matrix.

B. The number of all possible matrices of order 3×23\times2 with each entry either –1 or 1, is 64.

C. If PP is an invertible matrix, then PTP^T is also invertible.

D. If PP and QQ are square matrices of the same order, then ∣PQ∣=∣P∣+∣Q∣|PQ|=|P|+|Q|.

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 3

A: (PQT−QPT)T=QPT−PQT=−(PQT−QPT)(PQ^T-QP^T)^T=QP^T-PQ^T=-(PQ^T-QP^T), so it is skew symmetric. B: a 3×23\times2 matrix has 6 entries with 2 choices each, giving 26=642^6=64. C: (PT)−1=(P−1)T(P^T)^{-1}=(P^{-1})^T. D is false since ∣PQ∣=∣P∣∣Q∣|PQ|=|P||Q|.

2022: 30 Aug Shift 1

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