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!

Integral with e^x need help

  1. Sep 4, 2014 #1
    The problem I have is

    ∫(2e^x)/(e^x+e^-x)dx

    I cannot seem to get to the correct result, ln(e^2x + 1). I always have (e^2x)ln(e^2x + 1). What do I need to do, to get rid of the e^2x.
    Any help would be greatly appreciated.
     
  2. jcsd
  3. Sep 4, 2014 #2

    vela

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    Do the problem correctly. How's that for a nice vague reply? Unfortunately, that's about all anyone can say without seeing your work. How are we supposed to see where you're going wrong if you don't show your work?
     
  4. Sep 4, 2014 #3

    END

    User Avatar

    Step 1. Try to simplify the problem (i.e., take any constants out of the integral).

    Step 2. You may want to try u-substitution.
     
  5. Sep 4, 2014 #4
    Hint: What's the derivative of e^2x?

    I think this is probably where the mistake was made.
     
  6. Sep 6, 2014 #5
    Its simple. Multiply your numerator and denominator by e^x. This will get you (2e^2x)/(e^2x + 1)dx. Now suppose your whole denominator as another variable,say, t. Calculate dt which will be equal to 2e^2xdx.
    So now your integral is in the form of (1/t)dt. Integration of this will give you ln(t). Substitute back the value of 't' and there you have it.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Integral with e^x need help
  1. Integrate X²e^-x² (Replies: 11)

  2. Integrating e^(e^(x)) (Replies: 2)

  3. Integral of x(e^x) (Replies: 1)

Loading...