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nth Root of 2 Is Irrational (by Fermat-Wiles)

May 17, 2017Original blog post

A proof that the nth root of 2 is irrational for n ≥ 3, using Fermat's Last Theorem: hilariously overpowered, and valid.

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Free for classrooms, worksheets, slides and other non-commercial use under CC BY-NC 4.0, with credit to Ben Orlin.

Cartoon by Ben Orlin, Math with Bad Drawings. https://cartoons.mathwithbaddrawings.com/2017-05-17-nth-root-of-2-is-irrational/ (CC BY-NC 4.0)
Transcript

Suppose ⁿ√2 = a/b, n ≥ 3. 2 = aⁿ/bⁿ. 2bⁿ = aⁿ. bⁿ + bⁿ = aⁿ. This has no solutions, by Fermat-Wiles. Hence, [boxed] ⁿ√2 is irrational.

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Number & Arithmetic › Irrational NumbersNumber Theory › Fermat's Last TheoremLogic & Proof › Proof by ContradictionLogic & Proof › Proofs & TheoremsMathematicians & Scientists › Pierre de FermatMathematicians & Scientists › Andrew Wiles
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