Results 1 to 2 of 2

Math Help - newton raphson iterative method

  1. #1
    Newbie
    Joined
    Feb 2007
    Posts
    22

    newton raphson iterative method

    okay so i got a question conserning newton-raphson method to find a root to 4 d.p.

    the equation is e^x-3x = 0 now i've got the equation

    x_{n+1} = x_{n} - \frac{f(x_{n})}{f'(x_{n}}

    i have been given the information to start with x_{0} = 2.

    my question is how do i use the equation. I have no idea. I know what im looking for but i have no idea how to use the equation.

    Cheers guys!
    Last edited by mxmadman_44; August 19th 2007 at 12:59 PM. Reason: typo
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    9,820
    Thanks
    317
    Awards
    1
    Quote Originally Posted by mxmadman_44 View Post
    okay so i got a question conserning newton-raphson method to find a root to 4 d.p.

    the equation is e^x-3x = 0 now i've got the equation

    x_{n+1} = x_{n} - \frac{f(x_{n})}{f'(x_{n})}

    i have been given the information to start with x_{0} = 2.

    my question is how do i use the equation. I have no idea. I know what im looking for but i have no idea how to use the equation.

    Cheers guys!
    Ummm... Plug it into the formula?

    f(x) = e^x - 3x

    f^{\prime} = e^x - 3

    So
    x_{n+1} = x_n - \frac{f(x_n)}{f'(x_n)} =  x_n - \frac{e^{x_n} - 3x_n}{e^{x_n} - 3}


    With [tex]x_0 = 2 we have
    x_1 = 2 - \frac{e^2 - 3 \cdot 2}{e^2 - 3} \approx 1.6835182627834

    Then do it again with x_1 = 1.6835182627834 to get x_2, etc.

    I got an answer after about 5 iterations.

    -Dan
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Newton raphson method
    Posted in the Calculus Forum
    Replies: 5
    Last Post: April 4th 2011, 10:44 AM
  2. Newton Raphson method
    Posted in the Calculus Forum
    Replies: 4
    Last Post: May 24th 2010, 05:38 AM
  3. Newton-Raphson method
    Posted in the Calculus Forum
    Replies: 3
    Last Post: December 30th 2009, 06:13 AM
  4. Newton Raphson Method?????? HELP!
    Posted in the Calculus Forum
    Replies: 3
    Last Post: March 5th 2007, 08:37 AM
  5. Help- Newton - Raphson Method
    Posted in the Calculus Forum
    Replies: 3
    Last Post: July 12th 2006, 06:49 AM

Search Tags


/mathhelpforum @mathhelpforum