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Homework Help: Integration by Partial Fractions

  1. Oct 9, 2013 #1
    1. The problem statement, all variables and given/known data

    ∫ 4x/(x^3+x^2+x+1) dx

    3. The attempt at a solution

    I really dont know where to start, you cant complete the square, the degree of the numerator is less than the denominator so you cant use long division to simplify it.

    I cant really simplify the denominator as well, so im stuck.

    Help is greatly appreciated.!

    Edit: I dont need you to work out the whole problem, i just need help getting started.
    Last edited: Oct 9, 2013
  2. jcsd
  3. Oct 9, 2013 #2
    If you will look hard at the denominator you will see that it is a geometric sum. You can replace that long expression with something simpler, which is the sum of the terms. Not sure what that would be? Look up geometric sum.

    At that point maybe partial fractions will help.
  4. Oct 9, 2013 #3


    Staff: Mentor

    Try factoring the denominator. The rational root theorem says that there are only two possibilities for rational roots - and one of them does work.
  5. Oct 9, 2013 #4
    Solved. Thank you Mark
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