For the circuit shown in figure, Thevenin’s voltage and Thevenin’s equivalent resistance at terminals a – b is

The maximum power that can be transferred to the load resistor R_L from the voltage source in figure is

Impedance Z as shown in the figure is:

The region of convergence of z-transform of the sequence $${\left( {{5 \over 6}} \right)^n}u(n) - {\left( {{6 \over 5}} \right)^n}u( - n - 1)$$ must be