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Timeline for Elementary + short + useful

Current License: CC BY-SA 4.0

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Aug 2 at 14:18 history edited Martin Sleziak CC BY-SA 4.0
minor typos
Dec 20, 2013 at 7:29 comment added smyrlis @VictorProtsak: See edited version of my answer, were historical data are added.
Dec 20, 2013 at 7:27 history edited smyrlis CC BY-SA 3.0
Added historical data.
Dec 20, 2013 at 1:57 comment added Todd Trimble @VictorProtsak I've also heard it said that the proof of irrationality of $\sqrt{5}$, based on the geometry of the pentagon, may well have preceded that of $\sqrt{2}$.
Dec 20, 2013 at 1:56 comment added Todd Trimble @BenjaminDickman I agree with you; perhaps smyrlis would like to add more details.
Dec 20, 2013 at 1:46 comment added Victor Protsak In fact, there is some controversy as to whether the "traditional" even-odd reductio ad absurdum proof was the first one. Many sources assert that the original proof extended to irrationality of $\sqrt{d}$ for $d<17, d\ne 1,4,9,16,$ which would be consistent with not using elementary divisibility properties of primes. Also, some authors believe that a geometric proof involving the diagonal and the side of a square (the one that is equivalent to the non-termination of the continued fraction expansion of $\sqrt{2}-1$) was invented concurrently with or earlier than the even-odd argument.
Dec 19, 2013 at 23:44 comment added Benjamin Dickman @ToddTrimble Agreed; I think What would you do? ought to encompass more than just the stated theorem...
Dec 19, 2013 at 23:15 comment added Todd Trimble Well, there are by now many proofs, lending themselves to different directions and generalizations, and such might make for an interesting 30-minute lecture to undergraduates.
S Dec 19, 2013 at 22:45 history answered smyrlis CC BY-SA 3.0
S Dec 19, 2013 at 22:45 history made wiki Post Made Community Wiki by smyrlis