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# Integrating xlog(x) watch

1. Can somebody show me how to do this, having no luck with it - thanks!
2. Try using integration by parts.
3. That's what I've been doing, I have a load of answers but can't see which is correct.
4. u = ln x, du/dx = 1/x

dv/dx = x, v = (x^2)/2

Plop your numbers in into the by parts formula. Voila.

Whenever theres a lnx involved and its a product always makes u = lnx.
5. When doing a by parts problem the general rule is to let any power of x be the u term (ie. ,) EXCEPT when there is a log term in which case you make the log term the u term.
6. I get the answer as:

(X^2)(lnx)/2 - (x^3)/6

Is this correct?
7. Actually is the answer this:

(X^2)(lnx)/2 - 1/4(x^2)
8. yes.

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Updated: October 22, 2006
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