Can anyone give me a proof or some kind of general explaination about why there is a local max at (a,b) if D>0 and fxx<0, a min if D>0 and fxx>0, etc. My text book doesn't give any kind of explaination at all and I'm just a little curious as to why it works.(adsbygoogle = window.adsbygoogle || []).push({});

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# Homework Help: Test of Second Partials - Proof

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