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Since x is prime, then all positive numbers less than x will have no common factors with x, except 1. We can consider an example:6983manish wrote:If x is a positive integer, f(x) is defined as the number of positive integers which are less than x and do not have common factor with x other than 1. If x is prime then f(x) = ?
(A) x - 2
(B) x - 1
(C) (x + 1)/2
(D) (x - 1)/2
(E) 2
Anurag@Gurome wrote:Since x is prime, then all positive numbers less than x will have no common factors with x, except 1. We can consider an example:6983manish wrote:If x is a positive integer, f(x) is defined as the number of positive integers which are less than x and do not have common factor with x other than 1. If x is prime then f(x) = ?
(A) x - 2
(B) x - 1
(C) (x + 1)/2
(D) (x - 1)/2
(E) 2
If x = 5, then numbers less than 7 which have no common factors with 7 are 1, 2, 3, 4, 5, 6, the count of these numbers = 6, which is 1 less than 7.
So, if x is prime, then f(x) = x - 1
The correct answer is B.
You are welcome.rohu27 wrote:thanks Anurag, missed it completely.
We can plug in a prime number for x.6983manish wrote:If x is a positive integer, f(x) is defined as the number of positive integers which are less than x and do not have common factor with x other than 1. If x is prime then f(x) = ?
(A) x - 2
(B) x - 1
(C) (x + 1)/2
(D) (x - 1)/2
(E) 2
