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WAEC Further Mathematics 2025 Objective — Question 14

Question 14 of 40 from the West African Examinations Council (WAEC) Further Mathematics 2025 Objective paper, with the correct answer and a full explanation.

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

  • A. 1
  • B. 2
  • C. 3
  • D. 4Correct

Explanation

mn=4 and m+n=-k. Since (m+n)²=m²+n²+2mn, k²=8+2(4)=16, so k=±4. The positive value is 4.

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