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# The function f is defined for all positive integers n by the

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VP
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The function f is defined for all positive integers n by the [#permalink]

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11 Mar 2008, 22:26
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

The function f is defined for all positive integers n by the following rule: f(n) is
the number of positive integers each of which is less than n and has no positive
factor in common with n other than 1. If p is any prime number, then f(p)=

p - 1
p - 2
(p + 1)/2
(p - 1)/2
2
Director
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12 Mar 2008, 07:12
Answer should be P - 1.
All the numbers between 1 and P (excluding P) are less than P and has no positive factor in common with P other than 1 (because P is a prime number so factors other than 1 and P itself).

VP
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14 Mar 2008, 02:29
abhijit_sen wrote:
Answer should be P - 1.
All the numbers between 1 and P (excluding P) are less than P and has no positive factor in common with P other than 1 (because P is a prime number so factors other than 1 and P itself).

yes it is. it could be useful to try with numbers:

if P is 2 then we must have only 2 members: 1 and 2, so choice must be p-1
if P is 3 then we must have 1 and 2 as other members, so choice could be p-1 or p+1/2.

using both examples we would have p-1
Re: gprep functions   [#permalink] 14 Mar 2008, 02:29
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