Proving Irreducibility of Polynomials in Fields

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In summary, if f(x) is an irreducible polynomial of degree n in a field k, then the polynomial obtained by reversing the coefficients, a_n + a_n-1x+...+a_0x^n, is also irreducible. Eisenstein's Criterion may not be useful in this case and it may be helpful to consider the function f(y)/y^n where y = 1/x.
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playa007
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Homework Statement


Let k be a field, and let f(x) = a_0 + a_1x +a_2x^2 +...+a_nx^n in k[x] having degree n. If f(x) is irreducible, then so is a_n + a_n-1x+...+a_0x^n


Homework Equations





The Attempt at a Solution


A function that "reverses" the coefficients is not a well-defined function so it is necessary to use another approach. I'm wondering how this can be done, I'm pretty sure Eisenstein's Criterion isn't of much use here.

Any help would be highly appreciated.
 
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  • #2
playa007 said:
A function that "reverses" the coefficients is not a well-defined function
?
Is it any help that your second function is f(y)/y^n where y = 1/x ?
 

1. What does it mean to prove irreducibility?

Proving irreducibility means showing that a mathematical object, such as a polynomial or a number, cannot be broken down into smaller components or factors. This is often done by demonstrating that the object cannot be simplified or reduced to a simpler form.

2. Why is proving irreducibility important in mathematics?

Proving irreducibility is important in mathematics because it helps us understand the structure and properties of mathematical objects. It also allows us to solve problems and make predictions by breaking down complex systems into simpler, irreducible components.

3. How do you go about proving irreducibility?

The method for proving irreducibility depends on the specific mathematical object being studied. In general, it involves analyzing the object's properties and using logical reasoning to show that it cannot be reduced. This may involve techniques such as factoring, induction, or contradiction.

4. What are some common examples of irreducible objects?

Some commonly studied irreducible objects include prime numbers, irreducible polynomials, and irreducible elements in a ring. Other examples may include simple graphs, irreducible fractions, and irreducible representations in group theory.

5. Can you prove irreducibility in all cases?

No, it is not always possible to prove irreducibility in all cases. Some mathematical objects may be too complex or have properties that are not yet well understood. In these cases, mathematicians may work towards developing new techniques and theories to better understand and prove the irreducibility of these objects.

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