Most of the people I see gets confused about this rule. This rule actually cannot determine the number of roots. Specifically, this rule determines the NUMBER OF MAXIMUM real positive or negative roots by checking the number of change of signs in f(x) and f(-x). The word MAXIMUM should be given emphasis.

For the people who don't know this rule: Check this link
http://en.wikipedia.org/wiki/Descartes'*rule*of_signs

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## Comments

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TopNewestI think this rule also tells us about the complex roots.

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Obviously you can get the MAXIMUM number of complex roots by taking out the number of MAXIMUM real roots from the total roots

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Yes I've checked the wolfram. It also says this.

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Can you contribute to the wiki on Descartes Rule of Sign here on Brilliant ?

Thanks :)

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Sure, but can you tell me how can I contribute?

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It's simple really !

Just got to the link that I have provided, click on "edit this page" and add the content that you think is appropriate :)

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