Results 1 to 4 of 4
Like Tree2Thanks
  • 1 Post By FelixFelicis28
  • 1 Post By votan

Math Help - Evaluate the definite integral of x^(-1)

  1. #1
    Member dokrbb's Avatar
    Joined
    Feb 2013
    From
    ...from out there ;)
    Posts
    236
    Thanks
    21

    Evaluate the definite integral of x^(-1)

    I'm just starting calc II and I didn't manage to see a lot of examples, but from the basic information I have got so far I'm confused about this one:

     \int_{-6}^{-3} (x^{-1} + 4x) and by evaluating it I get  (ln|x| + 2x^{2}) that I need to evaluate from -3 to -6 , how do I evaluate the ln|x| for negative numbers, or there is a trick I don't see...

    thank you,
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Junior Member FelixFelicis28's Avatar
    Joined
    Jan 2013
    From
    Edinburgh, United Kingdom
    Posts
    70
    Thanks
    32

    Re: Evaluate the definite integral of x^(-1)

    The key here is that the argument of the logarithm is |x|, not just x.
    Thanks from dokrbb
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member dokrbb's Avatar
    Joined
    Feb 2013
    From
    ...from out there ;)
    Posts
    236
    Thanks
    21

    Re: Evaluate the definite integral of x^(-1)

    Quote Originally Posted by FelixFelicis28 View Post
    The key here is that the argument of the logarithm is |x|, not just x.
    so I can do in this way ln|x| = ln|-3| = ln3 ...
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Senior Member
    Joined
    Sep 2013
    From
    USA
    Posts
    321
    Thanks
    136

    Re: Evaluate the definite integral of x^(-1)

    yes
    Thanks from dokrbb
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. evaluate the definite integral
    Posted in the Calculus Forum
    Replies: 8
    Last Post: December 7th 2012, 12:26 PM
  2. Evaluate the definite Integral
    Posted in the Calculus Forum
    Replies: 8
    Last Post: December 21st 2009, 03:30 PM
  3. Evaluate definite integral
    Posted in the Calculus Forum
    Replies: 1
    Last Post: July 16th 2009, 10:40 AM
  4. evaluate the following definite integral
    Posted in the Calculus Forum
    Replies: 8
    Last Post: July 4th 2009, 05:38 AM
  5. evaluate definite integral
    Posted in the Calculus Forum
    Replies: 9
    Last Post: January 27th 2009, 08:20 PM

Search Tags


/mathhelpforum @mathhelpforum