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Math Help - Partial Fraction Decomposition

  1. #1
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    Partial Fraction Decomposition

    Find the partial fraction decomposition for the rational expression:
    (3x^3+4x)/(x^2+1)^2

    I know that you will have: A/? + B/? + C/? + D/? , but I don't know where to go from there.

    Thanks!
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  2. #2
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    Quote Originally Posted by ss103 View Post
    Find the partial fraction decomposition for the rational expression:
    (3x^3+4x)/(x^2+1)^2

    I know that you will have: A/? + B/? + C/? + D/? , but I don't know where to go from there.

    Thanks!
    \frac{Ax+B}{x^2+1}+ \frac{Cx+D}{(x^2+1)^2} = \frac{3x^3+4x<br />
}{(x^2+1)^2}

    Cross multiply by (x^2+1)^2 expand and equate coefficients wrt x. That will give you a system for A, B, C and D.
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  3. #3
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    Hi

    The form of the decomposition is \frac{Ax+B}{x^2+1} + \frac{Cx+D}{(x^2+1)^2}

    EDIT : too late !
    Last edited by running-gag; March 28th 2009 at 09:18 AM. Reason: Too late
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  4. #4
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    Okay so my answer is (3x/x^2+1) + (x/(x^2+1)^2).

    Is that right?
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  5. #5
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    Quote Originally Posted by ss103 View Post
    Okay so my answer is (3x/x^2+1) + (x/(x^2+1)^2).

    Is that right?
    I got that too.
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