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WAEC Further Mathematics 2007 Question 31

Question 31

Permutations and Combinations

Simplify nP3/nC2 + nP0

  1. A.n − 5
  2. B.n − 3
  3. C.2n − 1
  4. D.2n − 3
Show the answer and explanation

Answer: D (2n − 3)

Explanation

ⁿP₃/ⁿC₂ = n(n − 1)(n − 2) ÷ [n(n − 1)/2] = 2(n − 2) = 2n − 4, and ⁿP₀ = 1, giving 2n − 3.