Skip to main content

A Simple Proof that π is Irrational

  • Chapter
Pi: A Source Book
  • 663 Accesses

Abstract

Let π=a/b, the quotient of positive integers. We define the polynomials

EquationSource% MathType!MTEF!2!1!+- % feaagCart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGceaqabeaacaWGMb % GaaiikaiaadIhacaGGPaGaeyypa0ZaaSaaaeaacaWG4bWaaWbaaSqa % beaacaWGUbaaaOGaaiikaiaadggacqGHsislcaWGIbGaamiEaiaacM % cadaahaaWcbeqaaiaad6gaaaaakeaacaWGUbGaaiyiaaaacaGGSaaa % baGaamOraiaacIcacaWG4bGaaiykaiabg2da9iaadAgacaGGOaGaam % iEaiaacMcacqGHsislcaWGMbWaaWbaaSqabeaacaGGOaGaaGOmaiaa % cMcaaaGccaGGOaGaamiEaiaacMcacqGHRaWkcaWGMbWaaWbaaSqabe % aacaGGOaGaaGinaiaacMcaaaGccaGGOaGaamiEaiaacMcacqGHsisl % cqGHflY1cqGHflY1cqGHflY1cqGHRaWkcaGGOaGaeyOeI0IaaGymai % aacMcadaahaaWcbeqaaiaad6gaaaGccaWGMbWaaWbaaSqabeaacaGG % OaGaaGOmaiaad6gacaGGPaaaaOGaaiikaiaadIhacaGGPaGaaiilaa % aaaa!6D57!]]</EquationSource><EquationSource Format="TEX"><![CDATA[$$\begin{gathered} f(x) = \frac{{{x^n}{{(a - bx)}^n}}}{{n!}}, \hfill \\ F(x) = f(x) - {f^{(2)}}(x) + {f^{(4)}}(x) - \cdot \cdot \cdot + {( - 1)^n}{f^{(2n)}}(x), \hfill \\ \end{gathered}$$</EquationSource></Equation> the positive integer <Emphasis Type="Italic">n</Emphasis> being specified later. Since <Emphasis Type="Italic">n!f(x)</Emphasis> has integral coefficients and terms in <Emphasis Type="Italic">x</Emphasis> of degree not less than <Emphasis Type="Italic">n</Emphasis>, <Emphasis Type="Italic">f(x)</Emphasis> and its derivatives <Emphasis Type="Italic">f<Superscript>(<Emphasis Type="Italic">i</Emphasis>)</Superscript>(x)</Emphasis> have integral values for x=0; also for <Emphasis Type="Italic">x</Emphasis>=&#x03C0;<Emphasis Type="Italic">=a/b</Emphasis>, since <Emphasis Type="Italic">f(x) =f(a/b&#x2212;x)</Emphasis>. By elementary calculus we have <Equation ID="Equb"><EquationSource Format="MATHTYPE"><![CDATA[% MathType!MTEF!2!1!+- % feaagCart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaSaaaeaaca % WGKbaabaGaamizaiaadIhaaaWaaiWaaeaacaWGgbGaai4jaiaacIca % caWG4bGaaiykaiGacohacaGGPbGaaiOBaiaadIhacqGHsislcaWGgb % GaaiikaiaadIhacaGGPaGaci4yaiaac+gacaGGZbGaamiEaaGaay5E % aiaaw2haaiabg2da9iaadAeacaGGNaGaai4jaiaacIcacaWG4bGaai % ykaiGacohacaGGPbGaaiOBaiaadIhacqGHRaWkcaWGgbGaaiikaiaa % dIhacaGGPaGaci4CaiaacMgacaGGUbGaamiEaiabg2da9iaadAgaca % GGOaGaamiEaiaacMcaciGGZbGaaiyAaiaac6gacaWG4baaaa!63CA! ]]</EquationSource><EquationSource Format="TEX"><![CDATA[$$\frac{d}{{dx}}\left\{ {F'(x)\sin x - F(x)\cos x} \right\} = F''(x)\sin x + F(x)\sin x = f(x)\sin x$$

and

EquationSource% MathType!MTEF!2!1!+- % feaagCart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa8qmaeaaca % WGMbGaaiikaiaadIhacaGGPaGaci4CaiaacMgacaGGUbGaamiEaiaa % dsgacaWG4bGaeyypa0ZaamWaaeaacaWGgbGaai4jaiaacIcacaWG4b % GaaiykaiGacohacaGGPbGaaiOBaiaadIhacqGHsislcaWGgbGaaiik % aiaadIhacaGGPaGaci4yaiaac+gacaGGZbGaamiEaaGaay5waiaaw2 % faaaWcbaGaaGimaaqaaiabec8aWbqdcqGHRiI8aOWaa0baaSqaaiaa % icdaaeaacqaHapaCaaGccqGH9aqpcaWGgbGaaiikaiaadIhacaGGPa % Gaey4kaSIaamOraiaacIcacaaIWaGaaiykaaaa!60A7!]]</EquationSource><EquationSource Format="TEX"><![CDATA[$$\int_0^\pi {f(x)\sin xdx = \left[ {F'(x)\sin x - F(x)\cos x} \right]} _0^\pi = F(x) + F(0)$$
(1)

.

This is a preview of subscription content, log in via an institution to check access.

Access this chapter

Chapter
USD 29.95
Price excludes VAT (USA)
  • Available as PDF
  • Read on any device
  • Instant download
  • Own it forever
eBook
USD 74.99
Price excludes VAT (USA)
  • Available as PDF
  • Read on any device
  • Instant download
  • Own it forever

Tax calculation will be finalised at checkout

Purchases are for personal use only

Institutional subscriptions

Authors

Rights and permissions

Reprints and permissions

Copyright information

© 1997 Springer Science+Business Media New York

About this chapter

Cite this chapter

Niven, I. (1997). A Simple Proof that π is Irrational. In: Pi: A Source Book. Springer, New York, NY. https://doi.org/10.1007/978-1-4757-2736-4_33

Download citation

  • DOI: https://doi.org/10.1007/978-1-4757-2736-4_33

  • Publisher Name: Springer, New York, NY

  • Print ISBN: 978-1-4757-2738-8

  • Online ISBN: 978-1-4757-2736-4

  • eBook Packages: Springer Book Archive

Publish with us

Policies and ethics