Let f:R→R satisfy

f(a)≠0 for some a in R

f(xf(y))=yf(x) for all x,y in R
Prove that f(x)=f(x) for all x in R.
(In reply to
re(2): A final input by Bractals)
I think your function fails for x=2^r*3^q and y with f(y)=y.

Posted by JLo
on 20061230 06:35:23 