# Problem on functions

Guys please help me solve this problem(it is troubling me).......

Let f:R+ --> R be defined as f(x)=x + (1/x) -$$\lfloor$$ x + (1/x) $$\rfloor$$. It is required to prove that there are infintely many rational numbers u so that

$$\bullet\, 0<u<1,$$

$$\bullet\, u,\,f(u),\, f(f(u)) \:are\: all\: distinct,\: and$$

$$\bullet\, f(f(u))= \,f(f(f(u)))$$

Note by Nishant Sharma
5 years, 2 months ago

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a nice problem you gave but sorry i could not solve it...hope anyone comes forward to confront this problem...:(

- 5 years, 2 months ago

Is there no one who can help me out with this problem ? Not even Calvin sir ?

- 5 years, 2 months ago