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JAMB Mathematics 2005 Question 22

Question 22

Matrices and Determinants

If M and N are two matrices defined by M = (1 3 2; 4 5 −1; −3 2 0) and N = (1 −2 3; 4 −1 5; 2 −3 −1), evaluate 2M − 3N. (Matrices written row by row.)

  1. A.(−1 12 5; 4 7 13; 0 −5 −3)
  2. B.(−1 0 −5; −4 7 −17; 0 −5 3)
  3. C.(−1 12 −5; −4 13 −17; −12 13 3)
  4. D.(−1 12 −5; 4 13 13; −12 13 3)
Show the answer and explanation

Answer: C ((−1 12 −5; −4 13 −17; −12 13 3))

Explanation

2M = (2 6 4; 8 10 −2; −6 4 0) and 3N = (3 −6 9; 12 −3 15; 6 −9 −3). Subtracting entry by entry gives (−1 12 −5; −4 13 −17; −12 13 3).