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The theorem is named after Paolo Ruffini, who made an incomplete proof in 1799 [1] (which was refined and completed in 1813 [2] and accepted by Cauchy) and Niels Henrik Abel, who provided a proof in 1824. [3] [4] Abel–Ruffini theorem refers also to the slightly stronger result that there are equations of degree five and higher that cannot be ...
This is a key step in the proof that for every n > 4 there are polynomials of degree n which are not solvable by radicals (Abel–Ruffini theorem). This property is also used in complexity theory in the proof of Barrington's theorem.
The case of higher degrees remained open until the 19th century, when Paolo Ruffini gave an incomplete proof in 1799 that some fifth degree equations cannot be solved in radicals followed by Niels Henrik Abel's complete proof in 1824 (now known as the Abel–Ruffini theorem).
There exist algebraic solutions for cubic equations [1] and quartic equations, [2] which are more complicated than the quadratic formula. The Abel–Ruffini theorem, [3]: 211 and, more generally Galois theory, state that some quintic equations, such as + =, do not have any algebraic solution.
The Abel–Ruffini theorem provides a counterexample proving that there are polynomial equations for which such a formula cannot exist. Galois' theory provides a much more complete answer to this question, by explaining why it is possible to solve some equations, including all those of degree four or lower, in the above manner, and why it is ...
ATS theorem (number theory) Abel's binomial theorem (combinatorics) Abel's curve theorem (mathematical analysis) Abel's theorem (mathematical analysis) Abelian and Tauberian theorems (mathematical analysis) Abel–Jacobi theorem (algebraic geometry) Abel–Ruffini theorem (theory of equations, Galois theory) Abhyankar–Moh theorem (algebraic ...
The Abel–Ruffini theorem states that such a solution by radicals does not exist, in general, for equations of degree at least five. Évariste Galois showed that an equation is solvable in radicals if and only if its Galois group is solvable. The proof is based on the fundamental theorem of Galois theory and the following theorem.
Abel sent a paper on the unsolvability of the quintic equation to Carl Friedrich Gauss, who proceeded to discard without a glance what he believed to be the worthless work of a crank. [12] As a 16-year-old, Abel gave a rigorous proof of the binomial theorem valid for all numbers, extending Euler's result which had held only for rationals.