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Math Help - Finding the derivative of a composite function

  1. #1
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    Finding the derivative of a composite function

    How do i do this?

    the function i need to find the derivative of is y=5/(x-27.7)-4. I believe the way you do this is to state that : y = 5 / U - 4 when U = x-27.7 . .: y = 5U-1 -4-1
    dy/du = -5U^-2
    du/dx = 1

    dy/dx = dy/du * du/dx
    = -5U^-2
    = -5(x-27.7)^-2
    = -5/(x-27.7)^2

    is this correct or is there more to do?
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  2. #2
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    Quote Originally Posted by Ploppies View Post
    How do i do this?

    the function i need to find the derivative of is y=5/(x-27.7)-4. I believe the way you do this is to state that : y = 5 / U - 4 when U = x-27.7 . .: y = 5U-1 -4-1
    dy/du = -5U^-2
    du/dx = 1

    dy/dx = dy/du * du/dx
    = -5U^-2
    = -5(x-27.7)^-2
    = -5/(x-27.7)^2

    is this correct or is there more to do?
    Is y=5/(x-27.7)-4 meant to mean \displaystyle y= \frac{5}{x - 27.7} - 4 ? If so, then your answer is correct.
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  3. #3
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    oh yes, my bad , thank you
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