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Finding partial fraction expansions

  • #1

Homework Statement



3. Find the partial fraction expansions of the following polynomials


a) 10/[(s^2)(s^2+6s+10)]


The Attempt at a Solution


I assume i should expan the polynomial in the form A/s^2+B/s+(Cs+D)/(s^2+6s+10) but i stuck at finding B. Maybe my expansion is just wrong .. :(
 

Answers and Replies

  • #2
Dick
Science Advisor
Homework Helper
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The form of the expansion is correct. It should work.
 
  • #3
33,637
5,298
The main idea is that the equation
[tex]\frac{A}{s^2} + \frac{B}{s} + \frac{Cs + D}{s^2 + 6s + 10} = \frac{10}{s^2(s^2 + 6s + 10)} [/tex]
has to be true for any value of s except those that make one or more denominators vanish. If you pick four values of s you should get four equations in four unknowns, from which you should be able to get A, B, C, and D.
 
  • #4
378
2
Have found C?

C and B are related ...
 
  • #5
got it. thanks all
 

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