A discrete-time causal signal x[n] has the z-transform:
\(X\left( z \right) = \frac{z}{{z - 0.4}},\;ROC:\left| z \right| > 0.4\)
The ROC for z-transform of the even part of x[n] will be:1
same as the ROC of X(z)
2
0.4 < |z| < 2.5
3
|z| > 0.2
4
|z| > 0.8