Consider a discrete-time sequence
$x[n]=\begin{cases} (0.2)^{n}, & 0 \leq n \leq 7 \\ 0, & \text { otherwise } \end{cases}$
The region of convergence of $X(z)$, the $z$-transform of $x[n]$, consists of
- all values of $z$ except $z=0.2$
- all values of $z$
- all values of $z$ except $z=0$
- all values of $z$ except $z=\infty$
