A discrete-time LTI system is described by the difference equation
y[n] + 4y[n-1] + 3y[n-2] = x[n] + 5x[n-1] + 6x[n-2]
a) Draw a cascade or parallel form for the block diagram representation of the system
b) Determine the possible ROC's of this system. For each case determine causality and stability of the system.