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Math Help - Complex values

  1. #1
    MHF Contributor Mathstud28's Avatar
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    Complex values

    I am obviously ignorant of this topic but I was fiddling and

    the real part of some complex integrals resembel their actual integral?

    What is the correlation

    Re\bigg[\int[\ln(x+i)+\ln(x-i)]\bigg]dx
    Resembles \int\ln(x^2+1)dx

    Is this just conicidence?
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  2. #2
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by Mathstud28 View Post
    I am obviously ignorant of this topic but I was fiddling and

    the real part of some complex integrals resembel their actual integral?

    What is the correlation

    Re\bigg[\int[\ln(x+i)+\ln(x-i)]\bigg]dx
    Resembles \int\ln(x^2+1)dx

    Is this just conicidence?
    From the rules of logarithms
    ln(x + i) + ln(x - i) = ln((x + i)(x - i)) = ln(x^2 + 1)

    so the two had better not only "resemble" each other, they had better be the same!

    -Dan
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  3. #3
    MHF Contributor Mathstud28's Avatar
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    Quote Originally Posted by topsquark View Post
    From the rules of logarithms
    ln(x + i) + ln(x - i) = ln((x + i)(x - i)) = ln(x^2 + 1)

    so the two had better not only "resemble" each other, they had better be the same!

    -Dan
    Yeah I know that...that is what I meant when I said "fiddling" I was doing that integral and I didnt want to do sub and then parts so I said I wonder if taking the real part of the sperated log is the same?
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