Inverse laplace transform of

(s^2+4s)/(s^4+3s^2-4)

Question

Inverse laplace transform of

(s^2+4s)/(s^4+3s^2-4)

anonymous · Answer

breaking this down i got 

$$\frac{ (s+2)^{2}-4 }{ (s ^{2}+4)(s-1)(s+1) }$$

but if i use partial fractions how can I solve for A, when i cant cancel out the (s^2+4)?

what other method can I use?

anonymous · Answer

@experimentX

experimentx · Answer

looks like my guess was incorrect http://www.wolframalpha.com/input/?i=partial+fraction+%28%28s%2B2%29%5E2%E2%88%924%29%2F%28%28s%5E2%2B4%29%28s%E2%88%921%29%28s%2B1%29%29

anonymous · Answer

i do not know what that is

experimentx · Answer

that's okay ... just make use of partial fractions. I thought one term will be constant.

anonymous · Answer

i could just use w.a. im unsure how they did that though.

anonymous · Answer

i can find b and c using partial fractions no problem, but i do not know how they got A

experimentx · Answer

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