Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Little help? simple problem

  1. Dec 20, 2007 #1
    hello.. i´m a hs senior in ap calculus bc but i went out of the country for vacations and brough my calculus book with me... i´ve been trying to figure out integration by parts by myself but i stumbled on this problem:confused:
    i know it´s supposed to be simple but it is driving me nuts...

    xlnx dx

    thanks for helping :smile:
  2. jcsd
  3. Dec 20, 2007 #2
    integration by parts, note pick your u and dv carefully
    Last edited: Dec 20, 2007
  4. Dec 20, 2007 #3


    User Avatar
    Science Advisor
    Gold Member

    You have two choices (u=x and dv=lnxdx) or (u=lnx and dv=xdx). Choose the one you think will be easier to handle.
  5. Dec 23, 2007 #4
    Hint, d(ln x)/dx = 1/x....

    Oh, whatever: u = ln x, dv = x => du = 1/x, v = x^2/2.
    So you get (x^2 * ln x)/2 - Int(x/2, x). And you just gotta do that last integral.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?