Question

(P/F,i,n)(F/A,i,n)(F/P,i,n)(A/F,i,n)=

Answer 1

等于1啊
其中(P/F,i,n)和(F/P,i,n)互为倒数，
(F/A,i,n)和(A/F,i,n)互为倒数，乘积是1.