Limit term in symsum output

Hi ,the following code gives a limit term in the output which is of no use . How to remove it?

syms a n z;
assume(abs(z)>abs(a));

X_z=symsum(((a)*z^-1)^n,n,0,inf)
simplify(X_z)

[Alan Stevens]

To remove it you need to supply values for a and z.

[Shelby Sajjad]

But i want to keep answer in symbolic format. Actually i want to find z-transform without using inbuilt function. The answer through symsum is ok but this limit term is useless

[Alan Stevens]

Come to think of it, it's just a geometric progression, so the result is: 1 + (a/z)/(1 - a/z) or just z/(z - a), as long as |a/z|<1

[Shelby Sajjad]

But the answer from ztrans is z/z-a. Is there a way to get that?

[Alan Stevens]

The answer of z/(z-a) is what I put in my previous reply. (Note: not z/z-a, which reduces to 1-a)