1. Not finding help here? Sign up for a free 30min 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!

Integration of -e^(-absval(x))

  1. Mar 19, 2009 #1
    1. The problem statement, all variables and given/known data and equations
    Find [tex]\int[/tex] -1e-|x| between negative infinity and positive infinity.

    2. The attempt at a solution

    So I tried to just integrate using laws for logarithmic equations and got:
    e-|x| between negative infinity and positive infinity.
    Of course this leaves me with:
    e-∞-e-∞ = 0
    I know the answer is -2, but I am not sure how to get there. Help would be much appreciated.
     
  2. jcsd
  3. Mar 19, 2009 #2

    danago

    User Avatar
    Gold Member

    Try splitting the integral into two separate integrals over two separate domains.

    Use the fact that |x| = -x when x<0 and |x|=x for x>0.
     
  4. Mar 19, 2009 #3
    Thanks danago, I think i figured it out. I split the integral and added the integral of the function from 0 to infinity with -infinity to 0. The first one came out to -1 and the next came out to 1 respectively, giving me -2. I fail to see how I should have caught this before though since the function is defined at 0. I guess you could see that is symmetric and just double the integral from 0 to infinity?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Integration of -e^(-absval(x))
  1. Integral of arcsin x (Replies: 4)

  2. Integral abs(x) (Replies: 8)

Loading...