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JAMB Mathematics 2001 Question 18

Question 18

Matrices and Determinants

Given the matrix K = [2, 1; 3, 4], the matrix K2 + K + 1, where I is the 2 × 2 identity matrix, is

  1. A.[9, 8; 22, 23]
  2. B.[10, 7; 21, 24]
  3. C.[7, 2; 12, 21]
  4. D.[6, 3; 13, 20]
Show the answer and explanation

Answer: B ([10, 7; 21, 24])

Explanation

K2 = [7, 6; 18, 19]. Adding K = [2, 1; 3, 4] and I = [1, 0; 0, 1] gives [10, 7; 21, 24].