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Thread: More integration

  1. #1
    GO! use leech seed! qwertysaur's Avatar
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    Default More integration

    I have a very annoying problem that I can't get. =/

    ∫ (X + 1)/(x<sup>2</sup> + 4x + 8) dx

  2. #2
    I'm selling these fine leather jackets Aerith's Knight's Avatar
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    I just filled two pages with partial integrals, imaginary numbers, splitting equations and a whole bunch of other crap. Then I decided to look at the answer, which came to

    -0.5 * ArcTan[(2+x)/2] + 0.5*Log[x^2 +4x +8]

    Which will be annoyingly complicated. So could you check first if the question itself wasn't wrong?

    I can get you started by:

    ∫ (X + 1)/(x2 + 4x + 8) dx = ∫ X/(x2 + 4x + 8) dx + ∫ 1/(x2 + 4x + 8) dx

    Where ∫ 1/(x2 + 4x + 8) dx = ln(x2 + 4x + 8)/(2x + 4) + C

    Also, x2 + 4x + 8 = (x - 2 - 2j)(x - 2 + 2j), but I doubt that helps.


  3. #3
    GO! use leech seed! qwertysaur's Avatar
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    I feel bad that you had two pages of work to do, but I really appreciate it. I took the derivative of your answer, and now I get it. Thanks

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    SeeDRankLou's Avatar
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    Is the "X" a typo for "x", or is the "X" different than the "x"?

  5. #5
    Draw the Drapes Recognized Member rubah's Avatar
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    Sepho felt that he must share his solution with you all

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    Recognized Member Jessweeee♪'s Avatar
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    The day is saved!

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