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Math Help - Really Hard Trig Equation

  1. #1
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    Really Hard Trig Equation

    tan^3x-9tan^2x-3tanx+3=0

    Solve for x. Thanks for helping.
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  2. #2
    MHF Contributor Drexel28's Avatar
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    Quote Originally Posted by GamesonPlanes View Post
    tan^3x-9tan^2x-3tanx+3=0

    Solve for x. Thanks for helping.
    Are you sure that is the correct equation?
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  3. #3
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    Yes, that is the right one. Its a very hard problem, but its the right one.
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  4. #4
    MHF Contributor Drexel28's Avatar
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    Quote Originally Posted by GamesonPlanes View Post
    Yes, that is the right one. Its a very hard problem, but its the right one.
    Really? solve tan(u)^3-9tan(u)^2+3tan(u)+3=0 - Wolfram|Alpha
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    Im ABSOLUTELY sure its the right question. And its minus 3tanx btw.
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  6. #6
    MHF Contributor Drexel28's Avatar
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    Quote Originally Posted by GamesonPlanes View Post
    Im ABSOLUTELY sure its the right question.
    My point was that it looks like it has imaginary solutions. There may be some trig identity, look for one. Otherwise, let u=\tan(x) attempt to solve u^3-9u^2-3u+3=0 and go from there.
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  7. #7
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    Quote Originally Posted by Drexel28 View Post
    My point was that it looks like it has imaginary solutions. There may be some trig identity, look for one. Otherwise, let u=\tan(x) attempt to solve u^3-9u^2-3u+3=0 and go from there.
    factorise x^3 - 9x^2 - 3x + 3 - Wolfram|Alpha

    And since Wolfram finds it difficult ....
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