7. An LTI system is described by the difference equation
y[n] + 0.5y[n-1] = x[n] - 0.25x[n-1] with initial conditions y[-1] = 2
(a) (4 pts) Write down the system transfer function H(z)
(b) (2 pts) Sketch the pole-zero diagram of this system.
n ≥ 0 (zero initial conditions)