A linear system’s response to $ e^{2jt} $ is $ t*e^{-2jt} $, and its response to $ e^{-2jt} $ is $ t*e^{2jt} $.
What is the system’s response to $ \cos(2t) $?
Well, if we convert $ \cos(2t) $ using euler's formula, we get $ 1/2 * e^{2jt) + 1/2 * e^{-2jt} $.
