Results 1 to 5 of 5

Math Help - question about exponential function - based on Wikipedia

  1. #1
    Junior Member
    Joined
    Feb 2010
    Posts
    50

    question about exponential function - based on Wikipedia

    hi guys,

    I will truly appreciate your help about this particular question!

    I am wondering why the "the sum of the first n + 1 terms of the power series of the exponential function gives negative numbers"

    Exponential function - Wikipedia, the free encyclopedia - the figure on the right

    I am also not so good to understand the exponential function itself... but I hope someone could help me!

    THANK YOU
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,614
    Thanks
    1581
    Awards
    1
    Quote Originally Posted by problady View Post
    I am wondering why the "the sum of the first n + 1 terms of the power series of the exponential function gives negative numbers"
    What does the sentence in red above mean?
    Please give a full and complete answer.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Feb 2010
    Posts
    50
    Plate do you know a bit of Matlab? I think I will able to explain you better with the code...
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,614
    Thanks
    1581
    Awards
    1
    Quote Originally Posted by problady View Post
    Plate do you know a bit of Matlab? I think I will able to explain you better with the code...
    Is this a mathematics question or a programing question?
    If it is the latter, then I have no interest in it.
    If it is the former, then you have no need any code.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Super Member
    Joined
    Mar 2008
    Posts
    934
    Thanks
    33
    Awards
    1
    Quote Originally Posted by problady View Post
    hi guys,

    I will truly appreciate your help about this particular question!

    I am wondering why the "the sum of the first n + 1 terms of the power series of the exponential function gives negative numbers"

    Exponential function - Wikipedia, the free encyclopedia - the figure on the right

    I am also not so good to understand the exponential function itself... but I hope someone could help me!

    THANK YOU
    If I understand your question correctly, you are asking why the first few terms of the infinite series for the exponential function -- for example,
    1 + x + \frac{1}{2!} x^2 + \frac{1}{3!} x^3
    can take on negative values although the exponential function e^x is always positive.

    The reason is that the series only gives the exponential function in the limit. If you truncate the series and only take finitely many terms, you only get an approximation to e^x, and actually the approximation is only a good fit for values near zero. If you get far away from zero the approximation is poor, and you can get negative values. The more terms in the series you take, the better the approximation gets, and you can get further away from zero before you get in trouble. That's what the animated graph on Wikipedia is trying to show.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. exponential function on wikipedia
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: April 5th 2011, 11:03 AM
  2. Exponential function question....
    Posted in the Pre-Calculus Forum
    Replies: 4
    Last Post: September 16th 2010, 01:03 AM
  3. Finding extrema based on a function
    Posted in the Calculus Forum
    Replies: 1
    Last Post: November 23rd 2009, 07:17 PM
  4. Replies: 3
    Last Post: October 23rd 2008, 12:59 PM
  5. Replies: 2
    Last Post: March 30th 2008, 02:28 PM

Search Tags


/mathhelpforum @mathhelpforum