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Thread: Differentiating a function

  1. #1
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    Differentiating a function

    Hi, I'm getting a bit confused about a question and I was wondering if you could help me out with where to start.
    I need to find the first and second derivative of;

    f(x)=(2x3+2x2-5x-2)/(2(x2-1))

    So what would f'(x) and f''(x) equal?

  2. #2
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    Quote Originally Posted by Lilly View Post
    Hi, I'm getting a bit confused about a question and I was wondering if you could help me out with where to start.
    I need to find the first and second derivative of;

    f(x)=(2x3+2x2-5x-2)/(2(x2-1))

    So what would f'(x) and f''(x) equal?
    If f(x)=u/v there is a formula for f'(x) It is f'(x)=(vu'-uv')/v^2 To get f''(x) apply same formula again to f'(x)

  3. #3
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    will I need to apply the chain rule to v though?

  4. #4
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    Quote Originally Posted by Lilly View Post
    will I need to apply the chain rule to v though?
    Not necessarily. v = 2x^2 - 2 so v' is just 4x. You will have to do the chain rule to u, though.
    Last edited by srmichael; 05-10-2012 at 10:53 AM.
    "There are 10 types of people in this world - those who understand binary and those who don't."

  5. #5
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    Quote Originally Posted by Lilly View Post
    will I need to apply the chain rule to v though?
    v=2(x^2-1)=2x^2-2 So v'=4x

  6. #6
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    (af)'= af', for a a constant, is really more fundamental than the "chain rule".

    And, by the way, a question about how to find a derivative has nothing to do with "differential equations".
    Last edited by HallsofIvy; 05-10-2012 at 09:47 AM.

  7. #7

    Differentiating a function

    This is the different function, I am confused with this question my math is not more strong. But I hope It will be good and more interesting also.
    Last edited by Subhotosh Khan; 06-05-2012 at 04:52 PM. Reason: removed spamming URL

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