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Finding zero of function problem please help

  1. Apr 18, 2009 #1
    1. The problem statement, all variables and given/known data

    the function f(x)=tan(3^x) has one zero in the interval [0,1.4]. The derivative at this point is


    3. The attempt at a solution

    f'(x)= sec^2(3^x)*x3^(x-1) and i really cant seem to get a zero from that because i really dont know where to start and if im misinterpreting the problem please tell me that. Thanks
     
  2. jcsd
  3. Apr 18, 2009 #2
    Wait, what is the initial question?
    Are you trying to find roots of:

    [tex]y=\tan{(3^x})[/tex]
    http://img7.imageshack.us/img7/7748/tan3x.jpg [Broken]
     
    Last edited by a moderator: May 4, 2017
  4. Apr 18, 2009 #3
    If that's the case, your derivative is incorrect.

    [tex]f'(x) = 3^x \log(3) \sec^2({3^x})[/tex]
     
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