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JAMB Mathematics 1994 Question 24

Question 24

Matrices and Determinants

Solve for x and y in the matrix equation shown above: (1 1; 3 y)(x; 1) = (4; 1)

Diagram for this question
  1. A.x = −3, y = 8
  2. B.x = 8, y = 3
  3. C.x = 3, y = −8
  4. D.x = 8, y = −3
Show the answer and explanation

Answer: C (x = 3, y = −8)

Explanation

Multiplying out: x + 1 = 4 and 3x + y = 1. So x = 3, and then 9 + y = 1 gives y = −8.