How Euler Did Even More (cid:2)C 2015by TheMathematicalAssociationofAmerica,Inc. LibraryofCongressCatalogCardNumber2014953563 PrinteditionISBN:978-0-88385-584-3 ElectroniceditionISBN:978-1-61444-519-7 How Euler Did Even More C. Edward Sandifer Western Connecticut State University PublishedandDistributedby TheMathematicalAssociationofAmerica CouncilonPublicationsandCommunications FrankFarris,Chair CommitteeonBooks FernandoGouveˆa,Chair SpectrumEditorialBoard GeraldL.Alexanderson,Co-Editor JamesJ.Tattersall,Co-Editor VirginiaM.Buchanan ThomasL.Drucker RichardK.Guy DominicKlyve ShawneeL.McMurran DanielE.Otero JeanJ.Pedersen KennethA.Ross MarvinSchaefer FranklinF.Sheehan AmyE.Shell-Gellasch SPECTRUMSERIES The Spectrum Series of the Mathematical Association of America was so named to reflect its purpose:topublishabroadrangeofbooksincludingbiographies,accessibleexpositionsofoldor newmathematicalideas,reprintsandrevisionsofexcellentout-of-printbooks,popularworks,and othermonographsofhighinterestthatwillappealtoabroadrangeofreaders,includingstudentsand teachersofmathematics,mathematicalamateurs,andresearchers. 777MathematicalConversationStarters,byJohndePillis 99PointsofIntersection:Examples—Pictures—Proofs,byHansWalser.Translatedfromtheoriginal GermanbyPeterHiltonandJeanPedersen AhaGotchaandAhaInsight,byMartinGardner AlltheMathThat’sFittoPrint,byKeithDevlin BeautifulMathematics,byMartinErickson CalculusandItsOrigins,byDavidPerkins CalculusGems:BriefLivesandMemorableMathematics,byGeorgeF.Simmons Carl Friedrich Gauss: Titan of Science, by G. 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WiththeassistanceofGeraldL.AlexandersonandPeterRoss MathematicalApocrypha,byStevenG.Krantz MathematicalApocryphaRedux,byStevenG.Krantz MathematicalCarnival,byMartinGardner MathematicalCirclesVolI:InMathematicalCirclesQuadrantsI,II,III,IV,byHowardW.Eves MathematicalCirclesVolII:MathematicalCirclesRevisitedandMathematicalCirclesSquared,by HowardW.Eves MathematicalCirclesVolIII:MathematicalCirclesAdieuandReturntoMathematicalCircles,by HowardW.Eves MathematicalCircus,byMartinGardner MathematicalCranks,byUnderwoodDudley MathematicalEvolutions,editedbyAbeShenitzerandJohnStillwell MathematicalFallacies,Flaws,andFlimflam,byEdwardJ.Barbeau MathematicalMagicShow,byMartinGardner MathematicalReminiscences,byHowardEves MathematicalTreks:FromSurrealNumberstoMagicCircles,byIvarsPeterson AMathematicianComesofAge,byStevenG.Krantz Mathematics:QueenandServantofScience,byE.T.Bell MathematicsinHistoricalContext,,byJeffSuzuki MemorabiliaMathematica,byRobertEdouardMoritz MoreFallacies,Flaws,andFlimflam,EdwardJ.Barbeau MusingsoftheMasters:AnAnthologyofMathematicalReflections,editedbyRaymondG.Ayoub NewMathematicalDiversions,byMartinGardner Non-EuclideanGeometry,byH.S.M.Coxeter NumericalMethodsThatWork,byFormanActon NumerologyorWhatPythagorasWrought,byUnderwoodDudley OutoftheMouthsofMathematicians,byRosemarySchmalz PenroseTilestoTrapdoorCiphers...andtheReturnofDr.Matrix,byMartinGardner Polyominoes,byGeorgeMartin PowerPlay,byEdwardJ.Barbeau ProofandOtherDilemmas:MathematicsandPhilosophy,editedbyBonnieGoldandRogerSimons TheRandomWalksofGeorgePo´lya,byGeraldL.Alexanderson RemarkableMathematicians,fromEulertovonNeumann,byIoanJames TheSearchforE.T.Bell,alsoknownasJohnTaine,byConstanceReid ShapingSpace,editedbyMarjorieSenechalandGeorgeFleck SherlockHolmesinBabylonandOtherTalesofMathematicalHistory,editedbyMarlowAnderson, VictorKatz,andRobinWilson SixSourcesofCollapse:AMathematician’sPerspectiveonHowThingsCanFallApartintheBlink ofanEye,byCharlesR.Hadlock Sophie’sDiary,SecondEdition,byDoraMusielak Student Research Projects in Calculus, by Marcus Cohen, Arthur Knoebel, Edward D. Gaughan, DouglasS.Kurtz,andDavidPengelley Symmetry,byHansWalser.TranslatedfromtheoriginalGermanbyPeterHilton,withtheassistance ofJeanPedersen. TheTrisectors,byUnderwoodDudley TwentyYearsBeforetheBlackboard,byMichaelStuebenwithDianeSandford WhoGaveYoutheEpsilon?andOtherTalesofMathematicalHistory,editedbyMarlowAnderson, VictorKatz,andRobinWilson TheWordsofMathematics,byStevenSchwartzman MAAServiceCenter P.O.Box91112 Washington,DC20090-1112 800-331-1622 FAX:301-206-9789 Contents Preface....................................................................... xi Part 1: Geometry.................................................. 1 1 TheEulerLine(January2009).............................................. 3 2 AForgottenFermatProblem(December2008)............................... 10 3 AProductofSecants(May2008)........................................... 18 4 CurvesandParadox(October2008)......................................... 26 5 DidEulerProveCramer’sRule?(November2009—AGuestColumnby RobBradley).............................................................. 32 Part II: Number Theory.......................................... 39 6 Factoring F (March2007)................................................. 41 5 7 RationalTrigonometry(March2008)........................................ 45 8 Sums(andDifferences)thatareSquares(March2009)........................ 52 Part III: Combinatorics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 9 St.PetersburgParadox(July2007).......................................... 61 10 LifeandDeath–Part1(July2008).......................................... 67 11 LifeandDeath–Part2(August2008)....................................... 74 Part IV: Analysis ............................................... 81 12 e,π andi:Whyis“Euler”intheEulerIdentity(August2007)................. 83 13 Multi-zetaFunctions(January2008)......................................... 88 14 SumsofPowers(June2009)................................................ 95 15 ATheoremofNewton(April2008).........................................101 ix