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Math Help - Derivatives with both a and y

  1. #1
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    Smile Derivatives with both a and y

    Hello!
    I've tried to solve this problem, but I am not completely sure how to differentiate when there is both x and y.
    I would appreciate your help and explanation

    The problem:
    2x^2 - x - y^2 = 0

    dy/dx: x = 1 and y = 1
    = ?

    The correct answer is apparently: 3/2

    Thanks
    Last edited by Aminekhadir; October 4th 2009 at 08:20 AM. Reason: Wrong title - it was supposed to be x and y - not a and y!
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  2. #2
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    simply my friend

    first things first, u need to separate the variables and make this eq in terms of y

     y = sqrt(2x^2-x)

    now take the derivative of both sides
    the RHS is a bit tricky, its a chain rule problem.
    its turns out to be

     dy = (1/(2(2x^2-x)^1/2 )*(4x-1)

    plug in x = 1 and you should have your answer!



    gah i hate this LATEX stuff... im trying to make this look right



    dy = (1/2)*2(2x^2-x)^1/2 * (4x-1)
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  3. #3
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    thank you very much for your help
    But what does "sqrt" mean?
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  4. #4
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    sqrt = square root

    sorry i thought that it was the coding LATEX used
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