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Math Help - URGENT help on intergrals pleaseee

  1. #1
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    URGENT help on intergrals pleaseee

    please can someone help me intergrate these please :

    Tan -1x
    1 + x(squared) dx

    and.

    4cos3s ds

    many thanks people
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  2. #2
    MHF Contributor kalagota's Avatar
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    Quote Originally Posted by Stockport_ben View Post
    please can someone help me intergrate these please :

    Tan -1x
    1 + x(squared) dx

    and.

    4cos3s ds

    many thanks people
    i suppose the first question is this..

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

    set u = \tan ^{-1} x \Rightarrow du = \frac{1}{1+x^2} \, dx and that should be fine..

    for the second one, set u = 3s \Rightarrow du = 3ds and you can do it all the way..
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  3. #3
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    heya yea thst right for the first one could you please do a step by step as im relativeley know to all this intergral stuff if not dont worry
    thanks for the help
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  4. #4
    MHF Contributor kalagota's Avatar
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    ok..

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

    set u = \tan ^{-1} x \Rightarrow du = \frac{1}{1+x^2} \, dx

    then \int \frac{\tan ^{-1} x}{1+x^2} \, dx = \int u \, du = \frac{u^2}{2} + C = \frac{(\tan^{-1} x)^2}{2} + C..

    is that ok?
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  5. #5
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    yea thats perfect thanks
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