Question

Inverse laplace transform of

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

Answer 1

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?

Answer 2

@experimentX

Answer 3

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

Answer 4

i do not know what that is

Answer 5

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

Answer 6

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

Answer 7

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