Otherwise there is no unique solution.
Let f(x) = a(x-2)(x-b), where a and b are real to be determined. f(f(x)) has only one real zero 5, then 5 must be a multi-root. Then either f(x) - 2 = a(x-5)(x-5) or f(x) - b = a(x-5)(x-5) ( b cannot be 2....) . Now we almost done.
Assume f(x)'s coefficients are all real;
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回复:Assume f(x)'s coefficients are all real;
-jinjing-
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07/13/2011 postreply
20:37:56
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Did not read this before send my post, which is the same.
-wxcfan123-
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07/15/2011 postreply
16:41:21