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JAMB Mathematics 1999 Question 18

Question 18

Quadratic Equations

Three consecutive positive integers k, l and m are such that l2 = 3(k + m). Find the value of m.

  1. A.4
  2. B.5
  3. C.6
  4. D.7
Show the answer and explanation

Answer: D (7)

Explanation

Write l = k + 1 and m = k + 2: (k + 1)² = 3(2k + 2), so k² − 4k − 5 = 0 and k = 5 (positive). Then m = 7.