(2)双边左移序列的单边Z变换 X(2)=2x(nu(n)z 0 ZT[x(n+mu(n)]=2x(n+m)z n=0 ∑ x(n+m) m=∑x(k)=k n k ∑x(k)=4-∑x(k) k=0 k=0 |X()-∑x) k=03 （2）双边左移序列的单边Z变换 n n X z x n u n z −  = =  0 ( ) ( ) ( )       = −       = − = + = + = +       − = −  = − = − −  = −  = − +  = − 1 0 0 1 0 0 ( ) 0 ( ) ( ) ( ) ( ) ( ) ( ) [ ( ) ( )] ( ) m k m k k m k m k k k m m k n m n m n n z X z x k z z x k z x k z z x n m z z x k z ZT x n m u n x n m z