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RE: How to calculate the relative extrema of a cubic function by applying the criterion of the first derivative?

in StemSocial22 days ago

Good work but you forgot the importance of checking the second derivative. It has to be non zero for your first derivate zeros to be the max/min of the original function.
They also tell you (if they are non zero) whether your original has a minimum or maximum. If the second derivative is positive it means your first derivative is transfering from negative to positive at its zero and the original function first had a decline in values and after that rises in values which means it's a minimum. Vice versa for the maximum.

Should both derivatives be zero you have a saddle point in your original function.

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I will take into account your considerations for a future publication, since the objective of this one was to use the criterion of the first derivative. I will take into account the criterion of the second derivative for my next publication.

Greetings, I hope to continue reading your comments in my next posts.

since the objective of this one was to use the criterion of the first derivative.

My comment was trigger by exactly that thought. As I said, it can be misleading if the second is zero as well. In that case you might think you found an extreme while you are actually hitting on a saddle. While at it I added the discussion point about the difference between max and min.

Sorry if that was too exhausting, once I get triggered by math I cannot resist :-P

!BBH

Hello friend, of course I understand you, we are in contact, thanks for encouraging a good debate.

@carlos84! @hannes-stoffel likes your content! so I just sent 1 BBH to your account on behalf of @hannes-stoffel. (2/50)

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