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JAMB Mathematics 2003 Question 21

Question 21

Matrices and Determinants

A matrix P has an inverse P−1 = (1 −3; 0 1). Find P. (Matrices are written row by row.)

  1. A.(−1 3; 0 −1)
  2. B.(1 3; 0 −1)
  3. C.(1 −3; 0 −1)
  4. D.(1 3; 0 1)
Show the answer and explanation

Answer: D ((1 3; 0 1))

Explanation

P is the inverse of P−1. The determinant of (1 −3; 0 1) is 1, so its inverse is (1 3; 0 1).