(a) Please describe how to apply the Routh-Hurwitz criterion to determine the stability of LTI discrete-time system. (b) Consider design a compensator for the system to meet the phase margin criterion of 45 but leave the gain-crossover frequency unaffected. What type of cascade compensators (Lag, Lead, Lag-Lead) can fulfill the objectives? Explain your choice. (c) Please state the definition of Phase Margin and Gain Margin. (d) A digital filter has an impulse response, h[n]=0.6ⁿu[n]. If it is excited by a unit sequence, what is the final value of the response?