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Math Help - Derivatives

  1. #1
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    Question Derivatives

    I need to show that in:

    x^3 + y^3 = 6xy

    the 2nd derivative is:

    Dn^2 = 16xy (2x - y^2) ^-3

    how would i solve this?
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  2. #2
    MHF Contributor Mathstud28's Avatar
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    Quote Originally Posted by mandn View Post
    I need to show that in:

    x^3 + y^3 = 6xy

    the 2nd derivative is:

    Dn^2 = 16xy (2x - y^2) ^-3

    how would i solve this?
    Differentiate implicity

    the first derivatiev would be 3x^2+3y^2\frac{dy}{dx}=6x\frac{dy}{dx}+6y now solve for \frac{dy}{dx} and then do the same again
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  3. #3
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    ok lets try that
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  4. #4
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    ok i got that part but what do u do after this step ?
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  5. #5
    MHF Contributor Mathstud28's Avatar
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    Quote Originally Posted by mandn View Post
    ok i got that part but what do u do after this step ?
    After what step? if you are talking abou the step I showed you you should take the derivative again and solve for \frac{dy^2}{d^2x}

    and remember you will get a couple \frac{dy}{dx}

    you will have to sub these for your solved first derivative
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  6. #6
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    ok thanks
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  7. #7
    MHF Contributor Mathstud28's Avatar
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    Quote Originally Posted by mandn View Post
    ok thanks
    If you have any specific problems post them and we will do our best to walk you through them
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  8. #8
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    right i will. but need to try solving it first.
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  9. #9
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    k good luck
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