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WAEC Further Mathematics 2012 Question 33

Question 33

Binomial Theorem

Find the constant term in the binomial expansion of (2x − 3/x)8.

  1. A.90720
  2. B.1296
  3. C.1120
  4. D.672
Show the answer and explanation

Answer: A (90720)

Explanation

The general term is 8Cr(2x)8−r(−3/x)r; the constant term has r = 4: 70 × 16 × 81 = 90720.