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WAEC Further Mathematics 2013 Question 15

Question 15

Matrices and Determinants

Given that P = (y − 2 y − 1 / y − 4 y + 2) and |P| = −23, find the value of y. (Matrix written row by row; / separates the rows.)

  1. A.−4
  2. B.−3
  3. C.−1
  4. D.2
Show the answer and explanation

Answer: B (−3)

Explanation

|P| = (y − 2)(y + 2) − (y − 1)(y − 4) = 5y − 8 = −23, so y = −3.