AoPS Wiki talk:Problem of the Day/September 19, 2011

Revision as of 16:16, 19 September 2011 by Negativebplusorminus (talk | contribs)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

We know that $f(f(x))=x$ for this particular function. Since $(x,y)$ is on the graph, $y=f(x)$; since $(y,z)$ is on the graph, $z=f(y)=f(f(x))=x$. Thus, $f(x)=f(z)$, so the answer is $\boxed{\textbf{(C)}}$.