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Math Help - Need help with a few important homework questions

  1. #1
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    Need help with a few important homework questions

    Graph y^2=2xy

    The thing with this is that I just don't know how to solve for Y. Apparently I'm not supposed to divide Y from both sides?




    Also I have no idea how to do this next one.

    A machine is rolling a metal cylinder under pressure. The radius of the cylinder is decreasing at a constant rate of 0.05 inches per second and the volume is a constant 128(pi) cubic inches. At what rate is the length h changing when the radius r is 1.8 inches?



    And I'll just throw in this third one cuz I'm not sure if I did it right.

    What Values of c are guaranteed by the Mean Value Theorem for f(x)=(x-2)^3 on the interval [-1,2]?


    I got 2-(the square root of)3.


    Thanks
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  2. #2
    MHF Contributor Mathstud28's Avatar
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    Quote Originally Posted by sean1058 View Post
    Graph y^2=2xy

    The thing with this is that I just don't know how to solve for Y. Apparently I'm not supposed to divide Y from both sides?




    Also I have no idea how to do this next one.

    A machine is rolling a metal cylinder under pressure. The radius of the cylinder is decreasing at a constant rate of 0.05 inches per second and the volume is a constant 128(pi) cubic inches. At what rate is the length h changing when the radius r is 1.8 inches?



    And I'll just throw in this third one cuz I'm not sure if I did it right.

    What Values of c are guaranteed by the Mean Value Theorem for f(x)=(x-2)^3 on the interval [-1,2]?


    I got 2-(the square root of)3.


    Thanks
    For the first one just plot points..if you have to

    for the mean value one did you solve for c in the following

    3(c-2)^2=\frac{0+9}{2+1}?
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  3. #3
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    No I have this

    3(c-2)^2=\frac{0+27}{2+1}

    cuz the 3 is to the third power

    and I can't just plot points for that one, I have to solve it first.
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  4. #4
    MHF Contributor Mathstud28's Avatar
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    Quote Originally Posted by sean1058 View Post
    Graph y^2=2xy

    The thing with this is that I just don't know how to solve for Y. Apparently I'm not supposed to divide Y from both sides?




    Also I have no idea how to do this next one.

    A machine is rolling a metal cylinder under pressure. The radius of the cylinder is decreasing at a constant rate of 0.05 inches per second and the volume is a constant 128(pi) cubic inches. At what rate is the length h changing when the radius r is 1.8 inches?



    And I'll just throw in this third one cuz I'm not sure if I did it right.

    What Values of c are guaranteed by the Mean Value Theorem for f(x)=(x-2)^3 on the interval [-1,2]?


    I got 2-(the square root of)3.


    Thanks
    y^2-2xy=0\Rightarrow{(y-x)^2-x^2=0}
    so (y-x)^2=x^2\Rightarrow{|y-x|=|x|}\Rightarrow{y=x\pm|x|}
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  5. #5
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    Quote Originally Posted by sean1058 View Post
    Graph y^2=2xy

    The thing with this is that I just don't know how to solve for Y. Apparently I'm not supposed to divide Y from both sides?

    Thanks

    Well, you can't divide each side by y because it's y^2, so to undo that you would have to take the square root to get plain old y.

    Do you know polar coordinates? That could help possibly. Otherwise, the comment above this one is the best you will get.
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  6. #6
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    thanks

    if anybody can help me with that middle one it would be most appreciated
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  7. #7
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    nevermind i got it
    Last edited by sean1058; April 29th 2008 at 07:26 AM.
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