For cma's question

来源: 于 2011-07-23 10:19:59 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次

f=2/9(x-2)^2.  You can check that f(2)=0 and f(f(5))=0. So f(0)=8/9.