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integrate ln x watch

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    can someone tel me why this isnt correct

    according to this site, the answer should be xlnx

    thanks
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  1. File Type: pdf ln x.pdf (5.8 KB, 91 views)
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    I thought if you id it by parts you got xlnx - x
    My maths teacher told me to learn it so I havent actually worked it out cause i cant be bothered.
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    (Original post by manps)
    can someone tel me why this isnt correct

    according to this site, the answer should be xlnx

    thanks
    No, the site is correct. Type in "Log[x]" into the box and it will give the answer you are looking for.
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    (Original post by manps)
    can someone tel me why this isnt correct

    according to this site, the answer should be xlnx

    thanks
    that's the right answer in the pdf. (didn't check the working though, but it's likely to be right, isn't it?)
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    Was anyone else completely relaxed despite the prospect of P2 a day away? I have P2 on Wednesday yet I don't feel nervous. I'm actually more worried that I'm too relaxed...
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    (Original post by Yannis)
    that's the right answer in the pdf. (didn't check the working though, but it's likely to be right, isn't it?)
    The working is right.
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    Example
    Find ò ln x dx

    To integrate this, we use a trick, rewrite the integrand (the expression we are integrating) as 1.lnx . We then let v = ln x and du/dx = 1 .

    Hence ò ln x dx = x ln x - ò x (1/x) dx

    = x lnx - ò 1dx

    = x lnx – x + constant



    the site here had swapped the Vs and Us in the formula, damn them- use the exam book version
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    yeh thats what the pdf says..
 
 
 
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