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Math Help - please help me to solve the equation

  1. #1
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    please help me to solve the equation

    hi everyone...can anyone please solve for me the equation x^5 e^-3Inx - 4x=21....thank u
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  2. #2
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    Re: please help me to solve the equation

    No we will not, that's your job.

    A hint: \displaystyle \begin{align*} e^{-3\ln{x}} = e^{\ln{\left( x^{-3} \right)}} = x^{-3} \end{align*}, which means your equation becomes

    \displaystyle \begin{align*} x^5 e^{-3\ln{x}} - 4x &= 21 \\ x^5 \left( x^{-3} \right) - 4x &= 21 \\ x^2 - 4x &= 21 \\ x^2 - 4x - 21 &= 0 \end{align*}

    Surely you can solve this quadratic equation...
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  3. #3
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    Re: please help me to solve the equation

    thank u very much for solution
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