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Math Help - Exponential Tricky Problem Solving Task

  1. #1
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    Exponential Tricky Problem Solving Task

    Hi i have got this question but i cant do part c can anybody help with my question i attached the 2 photos ::::


    Exponential Tricky Problem Solving Task-image-1-.jpgExponential Tricky Problem Solving Task-image.jpg
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  2. #2
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    Re: Exponential Tricky Problem Solving Task

    I assume the equation is x = At^be^{-ct}. Using the derivative, express the maximum point (which is t = 30) through b and c. This gives you one equation. For the second equation, you can take x(4t) = x(t) / 2 where t = 30. After some cancellations, this gives you another linear equation on b and c. From these two equations you can find b and c. Then find A from x(30) = 0.2.

    The answer is below (for checking only).
    Spoiler:
    A = 0.071301182
    b = 0.429537559
    c = 0.014317919
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  3. #3
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    Re: Exponential Tricky Problem Solving Task

    Quote Originally Posted by emakarov View Post
    I assume the equation is x = At^be^{-ct}. Using the derivative, express the maximum point (which is t = 30) through b and c. This gives you one equation. For the second equation, you can take x(4t) = x(t) / 2 where t = 30. After some cancellations, this gives you another linear equation on b and c. From these two equations you can find b and c. Then find A from x(30) = 0.2.

    The answer is below (for checking only).
    Spoiler:
    A = 0.071301182
    b = 0.429537559
    c = 0.014317919
    I dont get it can you be specify and PM me
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  4. #4
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    Re: Exponential Tricky Problem Solving Task

    Which exactly recommendation don't you get?
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  5. #5
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    Re: Exponential Tricky Problem Solving Task

    The methodsbof getting answer u cant use derevitive u have to use exponential or log rules to do part c thats what teacher said
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  6. #6
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    Re: Exponential Tricky Problem Solving Task

    If you can't use derivatives, you can assume that the maximum of At^be^{-ct} occurs at t = b / c. Draw several graphs for various values of b and c and verify that this is the case. The rest of the recommendations in post #2 should still work.
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