Re: Irrationality of e^k



In article <GmD9e.38561$qO6.37464@trnddc05>,
Hans Engler <h.engler@xxxxxxxxxxx> wrote:
>Does anybody know an "elementary" proof that e^k is irrational for all
>integers k? By "elementary" I mean a proof that uses facts like the
>differential equation or functional equation for the exponential function,
>the Maclaurin series for e^x and ln(1+x), or possibly the limit formula lim
>(1+x/n)^n = e^x.

This is a special case of the elementary proof that e is transcendental,
given e.g. in Herstein, Topics in Algebra, Theorem 5.F. This proof uses
nothing more advanced than the mean value theorem.

Robert Israel israel@xxxxxxxxxxx
Department of Mathematics http://www.math.ubc.ca/~israel
University of British Columbia Vancouver, BC, Canada


.



Relevant Pages

  • Re: Irrationality of e^k
    ... By "elementary" I mean a proof that uses facts like the ... > differential equation or functional equation for the exponential function, ... and the english version probably as well. ...
    (sci.math.research)
  • Re: A functional-differential equation
    ... it is a "delay differential equation" ... ... On a special functional equation. ... By Laplace transform we've got: ...
    (sci.math)
  • Re: Irrationality of e^k
    ... Hans Engler wrote: ... > differential equation or functional equation for the exponential ...
    (sci.math)
  • Irrationality of e^k
    ... differential equation or functional equation for the exponential function, ... the Maclaurin series for e^x and ln, or possibly the limit formula lim ...
    (sci.math)
  • Irrationality of e^k
    ... differential equation or functional equation for the exponential function, ... the Maclaurin series for e^x and ln, or possibly the limit formula lim ...
    (sci.math.research)

Quantcast