Cho   X ( Z ) = Z Z − 2 . Tìm x ( n ) với | Z | > 2 . x ( n ) = − ( − 1 2 ) − n u ( − n 22/30Cho X ( Z ) = Z Z − 2 . Tìm x ( n ) với | Z | > 2 . x ( n ) = − ( − 1 2 ) − n u ( − n − 1 ) x ( n ) = ( 2 ) n u ( n ) x ( n ) = ( − 2 ) n − 1 u ( n ) x ( n ) = ( − 2 ) n u ( n ) x ( n ) = ( − 2 ) n u ( n − 1 ) Giải thíchChọn đáp án C