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I got the same derivative by using mod 3. | I got the same derivative by using mod 3. | ||
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Revision as of 05:09, 20 November 2008
I can show that -1 isn't a multiple root, but I don't think that's really answering the question. Can anyone elaborate?
I used Theorem 20.5. Let f = the polynomial in the question and take the derivative. Prove there is no common factor between f and f prime. I'm not sure if this is correct though.
right. that's what i was using, but can you tell me how you showed that they don't have common factors?
Well the derivative is $ F'(x)=x^7 $. the only factors of this are $ x $,$ x^2 $,$ x^3 $,$ x^4 $,$ x^5 $,& $ x^6 $.
Since F(x) has the +1, they can never share a common factor, right? Unless my derivative is wrong. I took it to be in $ Z_3 $, so the $ 21x^{20} $ term disappeared.
I got the same derivative by using mod 3.
I think you just have to show that f and f' dont have any factors in common with F
