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UI Post-UTME Mathematics 2025 (Model questions) Question 14

Question 14

Matrices and Determinants

If the matrix [x 2; 3 x] (first row x, 2; second row 3, x) has a determinant of 16, find x

  1. A.±4
  2. B.±5
  3. C.±√22
  4. D.±22
Show the answer and explanation

Answer: C (±√22)

Explanation

Determinant = x·x − 2·3 = x² − 6 = 16, so x² = 22 and x = ±√22.