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StevenMx December 16th, 2008 08:39 AM

I've got another interesting (I hope) problem and I hope you'll help me to solve it :) Well it goes like this: Determine all points, where function f has it's extremums, and define whether it is maximum or minimum, if:

Scott December 16th, 2008 10:19 AM

Re: Extremum
There is a theorem for twice-differentiable functions f(x, y) that if




then f(x, y) has a relative maximum at (x, y), and similarly a relative minimum if . (I believe it can be proved with Taylor's theorem.)

December 16th, 2008 10:25 AM

Re: Extremum
Think about partial derivatives.



Set each to 0. Solve [1] for y and sub into [2]. Then, solve for x.

You can get y by subbing the x's back into the y you found. Check the critical points by using the second partials derivative test. It can be found in any calc book.

StevenMx December 16th, 2008 11:13 AM

Re: Extremum
Thank you :) You are really helpful guys :)

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