# simple partial fractions help (warning complex analysis :P )

by trickae
Tags: analysis, complex, fractions, partial, simple, warning
 P: 85 1. The problem statement, all variables and given/known data the question can be ignored - it involves laplace and Z transforms of RLC ckts. Vc(s) = 0.2 ----------------- s^2 + 0.2s + 1 find the partial fraction equivalent such that it is :  -j(0.1005) + j (0.1005) -------------- ------------------ s + 0.1-(0.995) s + 0.1 + j(0.995) 2. Relevant equations none 3. The attempt at a solution  0.2 A B --------------- = --------------------- + ------------------- s^2 + 0.25 + 1 s + (0.1 - j(0.995))) s + (0.1 + j(0.995)) 0.2 = A(s + 0.1 + j(0.995)) + B(s + (0.1 - j0.995)) 0.2 = As + A(0.1 + j(0.995)) + Bs + B(0.1 - j0.995) so As + Bs = 0 or (A + B) = 0 or A = -B so 0.2 = j(0.995A) - j(0.995B) somethings not right - if i evaluate this I don't get anywhere near the answer
 P: 1,235 Well, check this: (s + 0.1 - I 0.995)(s + 0.1 + I 0.995) = 1.00002 + 0.2 s + s² there is a small inaccuracy ... but nothing more. Solve your last equation and turn to another exercice. What does that become: 0.2 = j(0.995A) - j(0.995B) if A=-B ?
 P: 85 sorry dude i'm still a little confused. thats just a rounding error from the J term.
P: 1,235

## simple partial fractions help (warning complex analysis :P )

I just wanted to say that, except for decimals, you did it correctly.
You should solve the last equation and conclude.
 P: 85 thanks man i got it now - actually my next question is a little off topic ... but how did i get a post stuck in this thread? http://physicsforums.com/showthread.php?t=166823&page=2 I don't understand the thread whatsover. ANyways thanks for the help i actually got the answer i'l put it up when i get home.

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