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WAEC Further Mathematics 2010 Question 6

Question 6

Binomial Theorem

The coefficient of the 7th term in the binomial expansion of (2 − x/3)10 in ascending powers of x is

  1. A.560/243
  2. B.841/243
  3. C.1120/243
  4. D.4481/241
Show the answer and explanation

Answer: C (1120/243)

Explanation

The 7th term is 10C6(2)4(−x/3)6. Its coefficient is 210 × 16 × 1/729 = 3360/729 = 1120/243.