1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Improper Integral problem

  1. Aug 7, 2013 #1
    1. The problem statement, all variables and given/known data

    1.Determine the divergence/convergence of the following improper integrals by the evaluation of the limit:

    [itex]\int_{0}^{∞} \frac{dx}{e^{-x} + e^{x}}[/itex]




    2. Relevant equations



    3. The attempt at a solution

    Let u = e^x
    ∴ du = e^x dx

    I ended up with:

    [itex]\int_{0}^{∞} \frac{u du}{u^{2} + 1}[/itex]
    I have no idea on how to integrate the above ...
     
  2. jcsd
  3. Aug 7, 2013 #2

    vanhees71

    User Avatar
    Science Advisor
    2016 Award

    substitute [itex]v=u^2[/itex].
     
  4. Aug 7, 2013 #3

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    Hi SirPlus! :smile:
    fine so far :wink:
    Sorry, but that's completely wrong (including the limits).

    Start again, and this time write it out carefully step-by-step, with no short-cuts! :smile:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted