( ) refers to the system that the import of goods need to apply for a license from the department concerned , and it is not allowed to import without the license .
【简答题】设系统由下面差分方程描述: y ( n )= y ( n - 1)+ y ( n - 2)+ x ( n - 1) ( 1 ) 求系统的系统函数 H ( z ) , 并画出极零点分布图; ( 2 ) 限定系统是因果的, 写出 H ( z ) 的收敛域。 ( 3 ) 限定系统是稳定性的, 写出 H ( z ) 的收敛域