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

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# Small doubt about sets

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