(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Let f be a continuous real-valued function of R^n. Show that [(x,y): x \in R^n, y > f(x)] is an open subset of R^{n+1}

2. Relevant equations

3. The attempt at a solution

If I am thinking about this right... Since f(x) goes from (-oo, y), this is an open subset, and as f is continuous, the domain of f(x) must be open, so x\in U is open.

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# Relatively open sets

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