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WAEC Further Mathematics 2022 Question 14

Question 14

Binomial Theorem

Find the coefficient of x2 in the binomial expansion of (x + 2/x2)5.

  1. A.10
  2. B.40
  3. C.32
  4. D.80
Show the answer and explanation

Answer: A (10)

Explanation

The general term ⁵Cᵣ x⁵⁻ʳ(2/x²)ʳ has power 5 − 3r. For x², r = 1: ⁵C₁ × 2 = 10.