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WAEC Further Mathematics 2019 Question 28

Question 28

Binomial Theorem

Find the coefficient of the third term in the binomial expansion of (2x + 3y/4)3 in descending powers of x.

  1. A.27y2/64
  2. B.27y2/8
  3. C.8y2
  4. D.9y2
Show the answer and explanation

Answer: B (27y2/8)

Explanation

The third term is ³C₂(2x)(3y/4)² = 3 × 2x × 9y²/16 = (27y²/8)x, so its coefficient (of x) is 27y²/8.