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Math Help - Questions part 4

  1. #1
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    Questions part 4

    7) Gravel is being dumped from a conveyor belt at a rate of 25 t3/min, and its coarseness is such that it forms a pile in the shape of a cone whose base diameter and height are always equal. How fast is the height of the pile increasing when the pile is 10 ft high? Give your answer correct to three decimal places.


    8) If f(x) + x^2[f(x)]^3 = 30 and f(1) = 3, find f '(1).
    Last edited by mr fantastic; October 8th 2009 at 05:13 PM. Reason: Questions moved to new thread
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    Quote Originally Posted by CFem View Post
    7) Gravel is being dumped from a conveyor belt at a rate of 25 t3/min, and its coarseness is such that it forms a pile in the shape of a cone whose base diameter and height are always equal. How fast is the height of the pile increasing when the pile is 10 ft high? Give your answer correct to three decimal places.


    8) If f(x) + x^2[f(x)]^3 = 30 and f(1) = 3, find f '(1).

    Ok, so now that you're done sending us all your homework, what about showing some selfwork? I mean, so that we won't think that you're expecting others to do ALL of it.

    Tonio
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  3. #3
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    All of it?

    It's not even a quarter of it.

    I only posted the ones I'm completely stonewalled on.
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  4. #4
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    Do you know the formula for volume of a cone? That would be a good place to start.
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  5. #5
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    Quote Originally Posted by CFem View Post
    [snip]

    8) If f(x) + x^2[f(x)]^3 = 30 and f(1) = 3, find f '(1).
    Re-write this as y + x^2 y^3 = 30. Use implicit differentiation to get dy/dx (the re-write makes it easier to see how to do this. The technique ought to be in your class notes or textbook if you're being given questions on it).

    Substitute y = 3 and x = 1 to get the required value of dy/dx.

    If you need more help please state what you've done and where you get stuck.
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