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

Why do you Tack on The Negative For this Integral

  1. Feb 7, 2012 #1
    If you integrate


    why do you end up with a negative in front of your answer

  2. jcsd
  3. Feb 7, 2012 #2

    Char. Limit

    User Avatar
    Gold Member

    Because using u-substitution, we get this:

    u = 1 - y, du = - dy

    And so...

    [tex]\int \frac{1}{1-y} dy = - \int \frac{1}{u} du[/tex]

    Integrating the right-hand side, we get - ln|u| + C, or - ln|1-y| + C.
  4. Feb 7, 2012 #3
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook