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How to see in what points the function changes

  1. Jan 15, 2009 #1
    in this function
    http://img72.imageshack.us/img72/7038/31777281zi5.gif [Broken]
    its impossible to find the extreme points

    how to find the points for which the function changes in sign??
    Last edited by a moderator: Apr 24, 2017 at 10:20 AM
  2. jcsd
  3. Jan 15, 2009 #2


    Staff: Mentor

    From your notes, f(x) = 2x - 4x + 1
    f'(x) is not equal to x*2^(x - 1) - 4. You are using the power rule for derivatives, but that applies only to xn.

    After you find the correct derivative, set it to 0. You might need to settle for approximate values for where f'(x) = 0.

    Based on the points you found, there has to be a minimum somewhere between x = -10 and x = 10.

    BTW, for such a simple function, I personally would like it better if you included all of the information on one page, rather than forcing readers to open another Web page to see it.
    Last edited by a moderator: Apr 24, 2017 at 10:20 AM
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