Finite-length sequence Example:x[n]=8[n]+8 [n-5] X(z)=∑x[1z"=∑(on]+δLn-5)z" n= -2z"+2nz”=1+z-1+ ROC:z>0 or entire z-plane,except z=0 Example:y[n]=δ[n]+δ[n+5] Y(z)=1+z,ROC:z<0o or entire z-plane,except z=o 2525 Finite-length sequence ROC z : 0  or entire z-plane, except z=0 Example: y n n n  = +      +5 ( ) 5 Y z = +1 z ， or entire z-plane, except z=∞ ROC z :   ( )   2 1 N n N n X z x n z = − = (    ) 5 0 5 n n   n n z = − = + −  5 5 1 1 z z     = + − =1+ 5 5 0 0 5 n n n n   n n z z = = − − = + −   Example: x n n n  = + −      5