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Homework Help: Improper Integrals / Antiderivatives.

  1. Jul 9, 2009 #1
    1. The problem statement, all variables and given/known data
    Evaluate each improper integral whenever it is convergent.

    1. S 1-infinity 4 / x

    2. S 4 - infinity 2/x^3/2

    2. Relevant equations

    3. The attempt at a solution

    I'm having trouble with antiderivatives. I understand how to do them when the problem is like x^4 + x^2 + 3 or something but anytime they're in like a fraction form I get lost and the first step in improper integrals is finding the antiderivative.
  2. jcsd
  3. Jul 9, 2009 #2


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    Homework Helper

    well firstly do you know what is d/dx (lnx) gives?

    Secondly 1/an = a-n
  4. Jul 9, 2009 #3
    ln x = 1/x right?

    So, 4/x would just be x2?
  5. Jul 9, 2009 #4


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    Homework Helper

    No. If you differentiate lnx with respect to x to get 1/x, and integration is the reverse of differentiation, then the integral of 1/x with respect to x gives what?
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