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)=
A. P-1
B. P-2
C. (P+1)/2
D. (P-1)/2
E. 2
Ans: A
我是解不出來
不知我認知的題意有錯嗎?
一方程式F(n)=P<n, (P,n)=1=>P和n互質
我所知道的就是F(P)=P
不懂答案是怎麼來的??
誰好心可不可以教教我???