(c) Is that possible to find out an expression of the FT of this periodic signal? If so, write down the expression, if not, state the reasons. 4. (20 marks) Consider an LTI system whose response to the input signal x()-e'u)+eu) is (a) Find the frequency response of this system. (b) Determine the corresponding unit impulse response h(0). (e) Find out one suitable LCCDE that can represent the input/output relationship of this system