JAMB Mathematics 1992 Question 22

Question 22

Matrices and Determinants

Use the matrices below to answer questions 22 and 23.
P = [x 3 0; 2 y 3; 4 2 z] (rows: x, 3, 0 / 2, y, 3 / 4, 2, z)
Q = [x 2 4; 3 y 2; 0 3 z] (rows: x, 2, 4 / 3, y, 2 / 0, 3, z)
When PT is the transpose of P, calculate |PT| when x = 0, y = 1 and z = 2

  1. A.48
  2. B.24
  3. C.−24
  4. D.−48
Show the answer and explanation

Answer: B (24)

Explanation

A matrix and its transpose have the same determinant. With x = 0, y = 1, z = 2: |P| = 0(2 − 6) − 3(4 − 12) + 0 = 24.