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JAMB Mathematics 2001 Question 20

Question 20

Matrices and Determinants

If P = [3, −2, 4; 5, 0, 6; 7, 5, −1], then −2p is

  1. A.[−6, 4, −8; 5, 0, 6; 7, 5, −1]
  2. B.[−6, 4, −8; −10, 0, 6; −14, 5, −1]
  3. C.[−6, −4, 2; −10, −2, −12; −14, −10, 2]
  4. D.[−6, 4, −8; −10, 0, −12; −14, −10, 2]
Show the answer and explanation

Answer: D ([−6, 4, −8; −10, 0, −12; −14, −10, 2])

Explanation

Multiply every entry of P by −2: the rows become (−6, 4, −8), (−10, 0, −12) and (−14, −10, 2).