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Math Help - integral using a table

  1. #1
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    integral using a table

    Hi,

    Can someone tell me if this correct, please?

    int. tan^-1xdx=xtan^-1x-1/2ln(1+x^2)+c

    I used the formula "tan^-1udu=utan^-1u-1/2ln(1+u^2)+c

    Thank you
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  2. #2
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    Quote Originally Posted by chocolatelover View Post
    Hi,

    Can someone tell me if this correct, please?

    int. tan^-1xdx=xtan^-1x-1/2ln(1+x^2)+c

    I used the formula "tan^-1udu=utan^-1u-1/2ln(1+u^2)+c

    Thank you
    Is it much to ask that you may use some of LaTeX or patentheses, pleaseż?

    Actually, this it's solved applyin' integration by parts. Show your attempt.
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  3. #3
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by chocolatelover View Post
    Hi,

    Can someone tell me if this correct, please?

    int. tan^-1xdx=xtan^-1x-1/2ln(1+x^2)+c

    I used the formula "tan^-1udu=utan^-1u-1/2ln(1+u^2)+c

    Thank you
    it's correct. please use the appropriate parentheses


    EDIT: I know you were required to use an integration table to find the answer, but Krizalid may be on to something. try doing it by parts--for practice
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  4. #4
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    Is it much to ask that you may use some of LaTeX or patentheses, pleaseż?
    Sorry. I've tried it, but I can't get it to work.
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  5. #5
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by chocolatelover View Post
    Sorry. I've tried it, but I can't get it to work.
    You can't get parenthesis to work???

    All we ask is some way to distinguish things like sq. 1 - x^2 from sq. (1 - x^2).
    -Dan
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  6. #6
    Math Engineering Student
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    Quote Originally Posted by chocolatelover View Post
    Sorry. I've tried it, but I can't get it to work.
    So, you can't, let's try!

    By the mythic integration by parts formula, we have that

    \int u\,dv=u\cdot v-\int v\,du

    We gotta integrate \arctan x

    So let's take u=\arctan x\implies du=\frac1{1+x^2}\,dx & dv=dx\implies v=x, the integral becomes to

    \int\arctan x\,dx=x\arctan x-\int\frac x{1+x^2}\,dx

    Now the one million dollar question: could you take it from there?

    __________

    Hey, you better see This!!!
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