If I want to prove that a non specified function f(x) that maps x -->x' is onto could I show that f(x) is one to one and that f(x')^-1 (the inverse function) is also one to one??(adsbygoogle = window.adsbygoogle || []).push({});

Would that be a valid justification to say that thus f(x) must be onto?

More specifically I am looking to prove that every strictly increasing function is onto.

Francesco

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

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

# Small doubt about sets

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