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    • Thread Starter

    Ok, this ones been peeing me off: (excerise 3D q 2, Heinemann)

    given that I(little n) = ∫ x(lnx)^n dx,

    show that I(little n) = x(lnx)^n - nI(little (n-1))

    I keep getting extra bits in the equation - am doing it by parts (of course)

    I split it to ∫ (lnx)^(n-1) x lnx

    use (lnx)^(n-1) as 'v'

    use lnx as 'du/dx' -> integrates to xlnx-x

    But cant get it to work - any suggestions?

    The question is actually

    I_n = INT (lnx)^n dx

    Integrate by parts with u = (lnx)^n and dv/dx = 1.
    • Thread Starter

    Thanks alot (especially for quick reply) - never thought of doing like that.
    Thats what I find hard about P5 - someone shows me, and I'm like 'sure, i understand that', but wouldnt be able to come up with the same method in the exam. *sigh*

    thats a p3 technique, its pretty much you either know it or you don't...
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Updated: June 18, 2004

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