Results 1 to 10 of 10

Math Help - integration help please!!!

  1. #1
    Newbie
    Joined
    Sep 2007
    Posts
    23

    integration help please!!!

    a definite integral, lower limit is 1, upper limit is the squre root of 3, integral is
    arctan(1/x) I know how to take the integral of arctan(x), but have no clue how I should go about doing this one, help?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by pcgamer03 View Post
    a definite integral, lower limit is 1, upper limit is the squre root of 3, integral is
    arctan(1/x) I know how to take the integral of arctan(x), but have no clue how I should go about doing this one, help?
    do integration by parts. \arctan \frac 1x is the part you differentiate. i think that should work

    you may want to make a substitution of u = 1/x first, but it should work without doing that
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Sep 2007
    Posts
    23
    what do i let u equal and what do i let dv equal, thats what i am having trouble with
    Follow Math Help Forum on Facebook and Google+

  4. #4
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by pcgamer03 View Post
    what do i let u equal and what do i let dv equal, thats what i am having trouble with
    u = arctan(1/x), dv = 1
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Sep 2007
    Posts
    23
    what is the derivative of arctan?
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Math Engineering Student
    Krizalid's Avatar
    Joined
    Mar 2007
    From
    Santiago, Chile
    Posts
    3,654
    Thanks
    11
    Ohh man, then integrating will be kinda hard for ya.

    I suggest you to brush up some of derivatives, after that see integration.
    Follow Math Help Forum on Facebook and Google+

  7. #7
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by pcgamer03 View Post
    what is the derivative of arctan?
    that is not a question you should be asking, for the following reasons:

    (1) it is something you should know by heart

    (2) if you don't know it by heart, it is a very quick google search, text-page flip, or notebook-page flip away

    nevertheless, i shall oblige you...

    \frac d{dx} \arctan u = \frac {u'}{1 + u^2} .......where u is a function of x, of course
    Follow Math Help Forum on Facebook and Google+

  8. #8
    Global Moderator

    Joined
    Nov 2005
    From
    New York City
    Posts
    10,616
    Thanks
    9
    \tan^{-1} \frac{1}{x} = \frac{\pi}{2}\cdot \frac{x}{|x|}- \tan^{-1} x
    Follow Math Help Forum on Facebook and Google+

  9. #9
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by Krizalid View Post
    Ohh man, then integrating will be kinda hard for ya.

    I suggest you to brush up some of derivatives, after that see integration.
    It's interesting to look at the sequence of posts:

    Quote Originally Posted by pcgamer03 View Post
    a definite integral, lower limit is 1, upper limit is the squre root of 3, integral is
    arctan(1/x) I know how to take the integral of arctan(x), but have no clue how I should go about doing this one, help?
    Quote Originally Posted by pcgamer03 View Post
    what do i let u equal and what do i let dv equal, thats what i am having trouble with
    Quote Originally Posted by pcgamer03 View Post
    what is the derivative of arctan?
    Is it just me or is the first logically inconsistent with the second and third?
    Follow Math Help Forum on Facebook and Google+

  10. #10
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by mr fantastic View Post
    It's interesting to look at the sequence of posts:






    Is it just me or is the first logically inconsistent with the second and third?
    i see what you are saying (if the poster was honest in the first post--about being able to find the integral of arctan(x), he would already know the answer to his/her two later posts), but i just let it slide
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 3
    Last Post: November 3rd 2010, 12:54 AM
  2. Replies: 2
    Last Post: November 2nd 2010, 04:57 AM
  3. Replies: 8
    Last Post: September 2nd 2010, 12:27 PM
  4. Replies: 2
    Last Post: February 19th 2010, 10:55 AM
  5. Replies: 6
    Last Post: May 25th 2009, 06:58 AM

Search Tags


/mathhelpforum @mathhelpforum