I'm frustrated beyond belief with a proof.(adsbygoogle = window.adsbygoogle || []).push({});

Suppose we have an continuous even function with a domain of all real numbers. Now this function has limit as x goes to negative infinty equal to l and the limit as x goes to positive infinty is also equal to l.

I want to show that this function will either have a maximum or a minimum.

I'm not sure at all how to show this rigorously since I don't know how to apply the definition of a limit to limits at infinity. I think it has to do with bounds. And I need to do this without first derivative test.

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# Maximum and Minimum Question?

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