Results 1 to 2 of 2

Math Help - Fun with Partial Fractions.. Kind of

  1. #1
    Newbie
    Joined
    Mar 2009
    Posts
    10

    Fun with Partial Fractions.. Kind of

    Question on Textbook.

    My teacher gave us some PDF's of a text... i'm wondering why this situation is the case...

     \frac{s^2+2s+3}{(s+1)(s^2+2s+2)} = A\frac{1}{s+1} + B\frac{s+1}{(s+1)+1} + C\frac{1}{(s+1)+1}

    it then states "where (s+1)(s^2+2s+2) = (s+1)((s+1)^2+1)"

    I understand how the denominator can break down.. but why is the denominator of the B and C fractions NOT squared???? This is confusing me a lot... They then go on to multipy the fractions out very oddly...

    <br />
\frac{[(s+1)((s+1)^2+1)](s^2+2s+3)}{(s+1)(s^2+2s+2)} = <br />


    <br />
A\frac{(s+1)((s+1)^2+1)}{s+1} + B\frac{(s+1)(s+1)((s+1)^2+1)}{(s+1)+1} + C\frac{(s+1)((s+1)^2+1)}{(s+1)+1}<br />

    Can someone clarify what is going on here by chance? I would think the denominators for B and C should be (s+1)^2+1 and that the numerators would only get multiplied so that the demoniators equaled that of the equation on the left....

    Any help is much appreciated!

    EDIT: I was so stumped at that part, i never looked further in the example... looking further in the problem, i think it was simply a typo. However, i still would like to ask why the coefficient for B is (s+1) instead of simply s (since only the s is squared before you break up the poly)..?
    Last edited by drewkx152; March 24th 2009 at 11:40 PM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor matheagle's Avatar
    Joined
    Feb 2009
    Posts
    2,763
    Thanks
    5
    I'm having trouble with these last two terms.

     \frac{s^2+2s+3}{(s+1)(s^2+2s+2)} = A\frac{1}{s+1} + B\frac{s+1}{(s+1)+1} + C\frac{1}{(s+1)+1}

     s^2+2s+2 does NOT factor into  ((s+1)+1)^2= (s+2)^2

    Is the orignal problem....  \frac{s^2+2s+3}{(s+1)(s^2+4s+4)} ?
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 0
    Last Post: April 28th 2010, 10:53 AM
  2. Partial Fractions
    Posted in the Algebra Forum
    Replies: 1
    Last Post: April 15th 2009, 06:07 AM
  3. Partial Fractions
    Posted in the Algebra Forum
    Replies: 2
    Last Post: January 4th 2008, 04:29 PM
  4. Partial Fractions
    Posted in the Pre-Calculus Forum
    Replies: 7
    Last Post: January 3rd 2008, 11:54 AM
  5. Partial Fractions
    Posted in the Calculus Forum
    Replies: 1
    Last Post: March 4th 2007, 09:40 AM

Search Tags


/mathhelpforum @mathhelpforum