Finding inverse Z transform with usage of tables (LTI and causal sequences)

1. How many types of methods are there to determine inverse Z-transform?
2. What is causal sequence in Z-transform?

How many types of methods are there to determine inverse Z-transform?

There are at least 4 different methods to do this: Inspection. Partial-Fraction Expansion. Power Series Expansion.

What is causal sequence in Z-transform?

The z-transform of a causal sequence x(n), designated by X(z) or Z(x(n)), is defined as. (5.1) where z is the complex variable. Here, the summation taken from n = 0 to n = ∞ is in accordance with the fact that for most situations, the digital signal x(n) is a causal sequence, that is, x(n) = 0 for n < 0.