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WAEC Further Mathematics 2007 Question 28

Question 28

Matrices and Determinants

Given that P = (4 9) and Q = (−1 −2; 3 2), which of the following operations is possible?

  1. A.−QP
  2. B.P2
  3. C.Q2P
  4. D.PQ
Show the answer and explanation

Answer: D (PQ)

Explanation

P is 1 × 2 and Q is 2 × 2. PQ needs columns of P (2) = rows of Q (2), so it works; QP, P² and Q²P do not.