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WAEC Further Mathematics 2025 Question 14

Question 14

Polynomials

If m and n are the roots of x2 + kx + 4 = 0 and m2 + n2 = 8, find the positive value of k.

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

Answer: D (4)

Explanation

m + n = −k and mn = 4. m² + n² = (m + n)² − 2mn = k² − 8 = 8, so k² = 16 and the positive value is k = 4.