Galois Theory - irreducibility over Q

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Homework Help Overview

The problem involves demonstrating the irreducibility of the polynomial \(x^n - a\) over the rational numbers \( \mathbb{Q} \), where \(a\) is a product of distinct primes and \(n\) is an integer greater than or equal to 2. This falls under the subject area of Galois Theory and polynomial irreducibility.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss various methods for proving irreducibility, including the rational root theorem and Eisenstein's criterion. Some express uncertainty about the applicability of these methods to the problem at hand.

Discussion Status

The discussion is ongoing, with participants exploring different approaches to the problem. Some guidance has been offered regarding the rational root theorem and Eisenstein's criterion, but there is no explicit consensus on the best method to apply.

Contextual Notes

Participants note confusion regarding the applicability of certain irreducibility tests and express a desire to clarify their understanding of the problem setup.

Kate2010
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Homework Statement



If a>1 is a product of distinct primes, show that xn-a is irreducible over Q for all n ≥ 2.

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The Attempt at a Solution



I am not really sure how to start this problem. Can anyone point me in the right direction?

I know tests for irreducibility for example Eisensteins Criterion or reduction modulo p but I don't think that these are helpful here?

Thanks for any help.
 
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Hi Kate2010! :smile:

How about the rational root theorem?
 
I like Serena said:
Hi Kate2010! :smile:

How about the rational root theorem?

That would only tell you it doesn't have any linear factors. I'm a little confused why Kate2010 thinks Eisenstein's criterion isn't applicable.
 
Dick said:
That would only tell you it doesn't have any linear factors. I'm a little confused why Kate2010 thinks Eisenstein's criterion isn't applicable.

Right.
Just looked up Eisenstein's criterion.
Looks like a good one. :)
 
Thanks guys - I was trying to make things more complicated than they were.
 

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