Simple partial fractions help (warning complex analysis :P )

[trickae]

Homework Statement

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)

Homework Equations

none

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

 

[lalbatros]

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 ?

 

[trickae]

sorry dude I'm still a little confused.

thats just a rounding error from the J term.

 

[lalbatros]

I just wanted to say that, except for decimals, you did it correctly.
You should solve the last equation and conclude.

 

[trickae]

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?

https://www.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.