(adsbygoogle = window.adsbygoogle || []).push({}); infinite set

1. The problem statement, all variables and given/known data

[itex]f: \mathbb{R} \rightarrow \mathbb{Q} [/itex],

show that there is a [itex] q \in \mathbb{Q}[/itex] st. [itex]f^{-1}(q)[/itex] is infinite set in [itex] \mathbb{R}[/itex].

2. Relevant equations

3. The attempt at a solution

how can we show that is true?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Infinite set

**Physics Forums | Science Articles, Homework Help, Discussion**