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NDA2011MathematicsPermutation and CombinationActual

What is the value of _ r=1 ^n P (n, r) r! ?

Options

  1. A2^n-1
  2. B2^n
  3. C2^ n-1
  4. D2^n+1

Correct answer

A. 2^n-1

Step-by-step solution

The correct answer is option A

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