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

In(x)/(1+exp(x)) from 2 to ∞?

  1. Nov 25, 2011 #1
    determine whether the integral In(x)/(1+exp(x)) from 2 to ∞? converges or diverges?
     
  2. jcsd
  3. Nov 26, 2011 #2

    nicksauce

    User Avatar
    Science Advisor
    Homework Helper

    What is this function In(x)? Do you mean ln(x)? Assuming so, I think you can do a simple comparison test:

    0 < ln(x) / (1+exp(x)) < x / (1+exp(x)) < x / exp(x)

    And it's fairly easy to show the integral of x/exp(x) converges.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook