# Math Help - Laplace -> time domain

1. ## Laplace -> time domain

heyya, I'm doing a major piece of coursework and I cant convert my S domain function back to time domain.

this is the equasion, I'm limited to only using certain transforms (listed below), I've tried everything i can think of, but it's just not going my way.

thanks for any help =D

list of permited transforms:

2. An alternative method of looking at it, if your not to firmiliar with laplace transforms then...

rearange : 1/s x 4/S^2+4
into the form : K1/S + K2w/S^2+w^2

thanks D.R

[EDIT] sorry, i should of been more clear, the two K's are different so i relabeled them K1 and K2

An alternative method of looking at it, if your not to firmiliar with laplace transforms then...

rearange : 1/s x 4/S^2+4
into the form : K1/S + K2w/S^2+w^2

thanks D.R

[EDIT] sorry, i should of been more clear, the two K's are different so i relabeled them K1 and K2
The partial fraction decomposition should be routine: $\frac{4}{s(s^2 + 4)} \equiv \frac{1}{s} - \frac{s}{s^2 + 2^2}$.

The inverse transform of this should be obvious: $1 - \cos (2t)$.