For each of the Z transforms below:
a. Sketch the Pole-Zero plot.
b. Indicate if there is a ROC for which it is stable.
c. Indicate if there is a ROC for which it is causal.
d. Indicate if there is a ROC for which it is both causal and stable.
1 - z^(-1)
1 - z^(-1)
X^2z = 1 + 2 - 11z^(-1)
1 + z^(-1) - 2z^(-2)
X^3z = 1 - 1z^(-1) + z^(-2)