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Math Help - Can't figure out equation !!!!!!!!!

  1. #1
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    Can't figure out equation !!!!!!!!!

    The equation that i cannot solve is

    (e^x + e^-x) / 2 = 4
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  2. #2
    Behold, the power of SARDINES!
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    Re: Can't figure out equation !!!!!!!!!

    Quote Originally Posted by ubhutto View Post
    The equation that i cannot solve is

    (e^x + e^-x) / 2 = 4
    Hint: The equation is quadratic in e^x

    First multiply the equation by 2e^{x} This gives

    (e^x)^2+1=8e^{x} \iff (e^{x})^2-8e^{x}+1=0

    If you want you can use the substition u=e^{x} to get the quadratic

    u^2-8u+1=0

    Can you finish from here?
    Thanks from ubhutto
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  3. #3
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    Re: Can't figure out equation !!!!!!!!!

    what was your final answer because my equation won't balance
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  4. #4
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    Re: Can't figure out equation !!!!!!!!!

    Quote Originally Posted by ubhutto View Post
    what was your final answer because my equation won't balance
    Some better questions:

    Did you follow what TheEmptySet told you to do?

    Do you know how to solve a Quadratic Equation?

    Where exactly did you get stuck?


    Why not show your working out? Then we can give you some more guidance.
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  5. #5
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    Re: Can't figure out equation !!!!!!!!!

    i figured it out its ln(8-sqrt(60))/2)
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  6. #6
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    Re: Can't figure out equation !!!!!!!!!

    That is ONE of the two possible answers. What is the other?
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