Q No 7: Sketch the pole-zero plot for each of the following z-transform and shade the region of convergence.
(a) X1(z) = (1 - 1/2 z^-1) / (1 + 2z^-1), ROC: |z| < 2
(b) X2(z) = (1 - 1/3 z^-1) / ((1 + 1/2 z^-1)(1 - 2/3 z^-1)), x2[n] causal
(c) X3(z) = (1 + z^-1 - 2z^-2) / (1 - 13/6 z^-1 + z^-2), x3[n] absolutely summable.