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JAMB Mathematics 2025 Question 23

Question 23

Matrices and Determinants

Determine x + y if (2 −3; −1 4)(x; y) = (−1; 8)
(matrices written row by row, rows separated by ';')

  1. A.3
  2. B.4
  3. C.7
  4. D.12
Show the answer and explanation

Answer: C (7)

Explanation

The matrix equation gives 2x − 3y = −1 and −x + 4y = 8. From the second, x = 4y − 8; substituting, 5y − 16 = −1, so y = 3 and x = 4. Hence x + y = 7.