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Classifying critical points in 3D, the indeterminant case

When finding the critical points of a function, z=f(x,y), and a critical point has a hessian matrix with the determinant equal to zero, how do you classify the critical point?

Please help!

Thanks in advance! :biggrin:
Use higher order tests, exactly as you would in the one-dimensional case.
Reply 2
Original post by BlueSam3
Use higher order tests, exactly as you would in the one-dimensional case.


Could you please be more specific? What tests should i use exactly?

Also, i think you mean the two dimension case...
Original post by supperrabbit
Could you please be more specific? What tests should i use exactly?

Also, i think you mean the two dimension case...


No, I mean the one dimensional case, of functions RR\mathbb{R}\to\mathbb{R}.

And the tests are basically exactly what you'd expect from generalising the versions for the one dimensional case.

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