>>851 追加
5次方程式から、6次、7次へ(下記)
全部、ガロア理論が元になっている

(参考)
https://en.wikipedia.org/wiki/Quintic_function
Quintic function (5次方程式)
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https://en.wikipedia.org/wiki/Sextic_equation
Sextic function (6次方程式)
Solvable sextics
Some seventh degree equations can be solved by factorizing into radicals, but other septics cannot. Évariste Galois developed techniques for determining whether a given equation could be solved by radicals which gave rise to the field of Galois theory.
Some sixth degree equations, such as ax6 + dx3 + g = 0, can be solved by factorizing into radicals, but other sextics cannot. Évariste Galois developed techniques for determining whether a given equation could be solved by radicals which gave rise to the field of Galois theory.
It follows from Galois theory that a sextic equation is solvable in terms of radicals if and only if its Galois group is contained either in the group of order 48 which stabilizes a partition of the set of the roots into three subsets of two roots or in the group of order 72 which stabilizes a partition of the set of the roots into two subsets of three roots.
There are formulas to test either case, and, if the equation is solvable, compute the roots in term of radicals.[1]
References
1. R. Hagedorn, General formulas for solving solvable sextic equations, J. Algebra 233 (2000), 704-757
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つづく


>>855
>ガロア原論文の話をしていて、そこにはラグランジュ分解式が何度もあらわれているのに
>なんでクラインの本がラグランジュ分解式を知らなくていい理由になるんだい？
>言い訳が酷すぎるね。

到達点および視点が、低すぎる
ガロア理論は、ラグランジュ分解式を包含し、それをはるかに超えた広がりを持つ
”ラグランジュ分解式＝ガロア理論”ではない

ガロア理論の中で、ラグランジュ分解式を使うことと
”ガロア理論は、ラグランジュ分解式を包含し、それをはるかに超えた広がりを持つ”こと
とは、矛盾しない