Re: Limit



On Sun, 14 Oct 2007 02:45:04 -0700, "Boen S. Liong"
<mr_bean_curdy@xxxxxxxxx> wrote:

On 14 Okt, 16:03, Thomas Nordhaus <thnord2...@xxxxxxxx> wrote:
Boen S. Liong schrieb:

Can somebody help with the limit?

How to derive:

limit(u->0) (1-u)^(-1/2) to be (1+0.5u)?

This surely isn't correct. The limit is equal to 1. (1+0.5*u) is the
first order Taylor-approximation however. Just compute it using the
definitions.



Boen S. Liong.

--
Thomas Nordhaus

It is correct. I quote from a math book. My hunch is it is from Taylor
series expansion. Use numerical for u, and you will see. Please check
before you say it is wrong.

(1 - 0)^(-1/2) = 1 and the limit you ask for is obviously 1.


The first three terms of the Maclaurin series for (1-u)^(-1/2) are

(1-u)^(-1/2) = 1 + 1/2 u + 3/4 u^2 / 2! + ...


The binomial series gives the same result. See (10) at
<http://mathworld.wolfram.com/BinomialSeries.html>


For a value of u close to 0,

(1-u)^(-1/2) is approximately equal to 1 + u/2


Regards,

Boen S. Liong
.



Relevant Pages

  • Re: Limit
    ... first order Taylor-approximation however. ... Thomas Nordhaus ... series expansion. ... Boen S. Liong ...
    (sci.math)
  • Re: Limit
    ... Boen S. Liong schrieb: ... first order Taylor-approximation however. ... Thomas Nordhaus ... series expansion. ...
    (sci.math)