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Checking an answer

  1. Dec 9, 2007 #1
    1. The problem statement, all variables and given/known data


    the antiderivative of (-4x)/(x^2 + 3) dx





    2. Relevant equations



    3. The attempt at a solution

    i got -2+c is that right at all, if not can somebody help me
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Dec 9, 2007 #2
    If your answer is:

    -2 + c

    Then no, not even in the ballpark.

    Please explain what you did to arrive there.

    Note "antiderivative" is the same as "indefinite integral".

    To check your answer, take the derivative. If you arrive at the question, you have the right answer.

    (Unless of course you had a definite integral, in which case -2 + c could be correct after evaluating the integral on its parameters.)
     
  4. Dec 9, 2007 #3

    Defennder

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    Homework Helper

    Here's a hint to get you going:

    There's a special technique of integration if you want to find integral of f'(x)/f(x). Note that you can easily express the integral in that form.
     
  5. Dec 9, 2007 #4

    cristo

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    Staff Emeritus
    Science Advisor

    rayray; please note that you must start showing some work here in order for us to help you. Simply quoting an answer does not show what effort you have made, or even what you have done to get your answer. In this question for example, I have no idea what you have done to get your answer; but if you showed your work, I would probably be able to point out your mistakes.

    As for the actual approach; I would take Defennnder's advice and try to recall how to integrate f'/f.
     
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