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Math Help - struggling to find a dirivative

  1. #1
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    struggling to find a dirivative

    How do i find the dirivative of y=x-1/2x^2.
    Thats. y=x - 1 divided by 2x to the power 2.

    Any help would be greatful.
    Thanks, James.

    (where does the math notations everyone seems to use come from? )
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  2. #2
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    Krizalid's Avatar
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    Split the fraction in two pieces, then use the power rule for derivatives.

    --

    LaTeX stuff can be found here.
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  3. #3
    Bar0n janvdl's Avatar
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    Quote Originally Posted by james jarvis View Post
    How do i find the dirivative of y=x-1/2x^2.
    Thats. y=x - 1 divided by 2x to the power 2.

    Any help would be greatful.
    Thanks, James.

    (where does the math notations everyone seems to use come from? )
    We use Latex. (I'll go search for the tutorial and then edit my post and paste it here okay?)

    ( \frac{x - 1}{2x} )^{2}

    = (x(2x)^{-1} - 1(2x)^{-1})^{2}

    = \frac{1}{4} - \frac{1}{2} x^{-1} + \frac{1}{4}x^{-2}

    \frac{dy}{dx} = 0 + \frac{1}{2} x^{-2} - \frac{1}{2}x^{-3}

    = \frac{1}{2x^2} - \frac{1}{2x^3}

    ---------------

    EDIT: Krizalid gave you the link
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  4. #4
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    Thanks for reply. Always makes sense when you see it!
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  5. #5
    Bar0n janvdl's Avatar
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    Quote Originally Posted by james jarvis View Post
    Always makes sense when you see it!
    You bet!
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  6. #6
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    How to find derivative

    Your question is not clear.

    a) Is the 2x under the 1 only or under x as well?

    b) Is it (2)(x^2) or is it (2x)^2. That is, is it just the x that is raised to power 2 or the 2x?

    Tell me which is which and I will tell you......how
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  7. #7
    Bar0n janvdl's Avatar
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    Quote Originally Posted by jackddog View Post
    Your question is not clear.

    a) Is the 2x under the 1 only or under x as well?

    b) Is it (2)(x^2) or is it (2x)^2. That is, is it just the x that is raised to power 2 or the 2x?

    Tell me which is which and I will tell you......how
    Well my approach seems to be correct as he seems happy with it
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  8. #8
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    I think you use the Quotient Rule.
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