Results 1 to 7 of 7

Math Help - Antiderivative Question

  1. #1
    Newbie
    Joined
    Dec 2008
    Posts
    6

    Exclamation Antiderivative Question

    The directions state: Find the indefinite integral and check the result by differentiation.

    Here is the equation. (Please open the link below. I drew the equation on a paint program. I did not know how to post otherwise. Sorry.)
    http://i34.tinypic.com/24qntol.jpg

    If someone could please try this problem. When I did this I got an answer that did not check correctly with the original equation.
    Thank you!!!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,698
    Thanks
    454
    \frac{x^2+2x-3}{x^4} = \frac{x^2}{x^4} + \frac{2x}{x^4} - \frac{3}{x^4} = x^{-2} + 2x^{-3} + 3x^{-4}

    can you integrate the last expression?
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member Ziaris's Avatar
    Joined
    Dec 2008
    Posts
    26
    Split this up into seperate integrals by distributing the denominator of the fraction,

    \int\frac{x^2+2x-3}{x^4}dx=\int\frac{x^2}{x^4}dx+\int\frac{2x}{x^4}  dx-\int\frac{3}{x^4}dx.

    Now can you do it?
    Last edited by Ziaris; December 9th 2008 at 05:04 PM. Reason: typo
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Dec 2008
    Posts
    6

    Mine

    That's what I got too. I ended up getting:
    http://i37.tinypic.com/308v5o2.jpg

    I went and checked and I couldn't get the -x^-1 to work right. Could some one check me please?
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member Ziaris's Avatar
    Joined
    Dec 2008
    Posts
    26
    \frac{d}{dx}(-x^{-1}-x^{-2}+x^{-3})=x^{-2}+2x^{-3}-3x^{-4}

    so

    \frac{df}{dx}=\frac{1}{x^2}+\frac{2}{x^3}-\frac{3}{x^4}=\frac{x^2}{x^4}+\frac{2x}{x^4}-\frac{3}{x^4}=\frac{x^2+2x-3}{x^4}.

    You were right.
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Newbie
    Joined
    Dec 2008
    Posts
    6

    Antiderivate

    I understand how to rewrite the equation so I can take the antiderivative but I guess what I have a question about now is taking the antiderivative....
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Newbie
    Joined
    Dec 2008
    Posts
    6

    Thanks

    Oh I was right?

    That makes me feel better. Thank you so much!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. antiderivative question
    Posted in the Calculus Forum
    Replies: 7
    Last Post: February 13th 2010, 07:36 PM
  2. antiderivative question - help
    Posted in the Calculus Forum
    Replies: 7
    Last Post: January 19th 2010, 08:10 PM
  3. Antiderivative question
    Posted in the Calculus Forum
    Replies: 7
    Last Post: November 26th 2009, 06:01 PM
  4. Antiderivative question 2
    Posted in the Calculus Forum
    Replies: 1
    Last Post: February 15th 2009, 02:52 PM
  5. Antiderivative question
    Posted in the Calculus Forum
    Replies: 1
    Last Post: March 18th 2006, 03:43 PM

Search Tags


/mathhelpforum @mathhelpforum