Why no general solution to quintic equations?

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Discussion Overview

The discussion revolves around the existence of a general solution for quintic equations and higher-degree polynomials, exploring the implications of the Abel-Ruffini theorem and the nature of mathematical proofs related to this topic.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants express curiosity about the possibility of a general solution for quintic equations that may not have been discovered yet.
  • One participant cites the Abel-Ruffini theorem, stating that no general solution exists using only basic arithmetic operations and nth roots.
  • Another participant mentions that while quintic equations can be solved using Jacobi theta functions, this does not involve a finite number of elementary functions.
  • There is a discussion about the mathematical background required to understand the proof of the non-existence of a general solution, with references to abstract algebra and Galois theory.
  • One participant notes that there are various unsolved problems in mathematics, suggesting that the complexity of the issue is akin to the unpredictability of ordering a meal at a restaurant.

Areas of Agreement / Disagreement

Participants express differing views on the existence of a general solution for quintic equations. While some reference established theorems indicating no such solution exists under certain conditions, others propose alternative methods or functions that could potentially provide solutions.

Contextual Notes

The discussion highlights the limitations of understanding the proof of the non-existence of a general solution, particularly the dependence on advanced mathematical concepts and the varying interpretations of what constitutes a solution.

Superhoben
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It seems odd to me that we have no general solution to quintic equations yet.
Is it possible that it exist any general solutions to equations of the fifth degree (and higher) that just haven't been discovered yet?
Or are we certain that it doesn't exist?
 
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It is in fact a theorem that no solution exists that only uses functions that we would consider typical.

http://en.wikipedia.org/wiki/Abel–Ruffini_theorem

The theorem says that you cannot solve the general fifth degree polynomial using only basic arithmetic operations and calculating nth roots of numbers. It might be that there are other functions which you can allow yourself to use to solve higher degree polynomials (a trivial example is that if you define a function P(a,b,c,d,e) to return a root for a polynomial whose coefficients are a,b,c,d and e then you have "solved" the polynomial).
 
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Thanks. I don't understand why it don't exist yet and I don't understand the proof completely. Just out of curiosity, how much math do you need to read to understand the proof?
 
Superhoben said:
Thanks. I don't understand why it don't exist yet
It exists yet: The roots of the quintic equation can be analytically expressed thanks to the Jacobi theta functions, but not with a finie number of elementary functions.
 
Superhoben said:
Thanks. I don't understand why it don't exist yet and I don't understand the proof completely. Just out of curiosity, how much math do you need to read to understand the proof?
A fairly large portion of a typical undergraduate course in abstract algebra. For example, the proof using Galois theory is given in the final chapter (33) of Pinter's A Book of Abstract Algebra, and it depends to some degree on almost all of the first 32 chapters.

There are more direct proofs that do not use Galois theory - indeed, Abel's original proof predated Galois theory. Here is a video which sketches one such proof:

 
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There's all sorts of unsolved and insoluble problems in mathematics. It's not like walking into a restaurant and ordering a meal.
 

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