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Math Help - anti derivative?????????

  1. #1
    Member sluggerbroth's Avatar
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    anti derivative?????????

    x/(x+1)

    i let u=x+1
    so x=u-1

    i get answer of

    x+1-ln x +c

    book has answer of
    x - ln x +c

    what happened to the 1????
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  2. #2
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    Re: anti derivative?????????

    Quote Originally Posted by sluggerbroth View Post
    x/(x+1)

    i let u=x+1
    so x=u-1

    i get answer of

    x+1-ln x +c

    book has answer of
    x - ln x +c

    what happened to the 1????
    Both are correct. Notice that 1 + constant is still a constant.

    I am not sure how you could get x + 1 - ln|x| + C though...
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  3. #3
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    Re: anti derivative?????????

    Hint: \frac{x}{x+1} = 1 - \frac{1}{x+1}.
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