Given:
For a linear system we have:
$ e^{j2t} \rightarrow [system] \rightarrow te^{-j2t}\! $ $ e^{-j2t} \rightarrow [system] \rightarrow te^{j2t}\! $
To find the response of the system above we first note that $ e^{j2t} = cos(2t) + jsin(2t)\! $
