整理(1)式得全响应 Y(z)= 2Z (z+1Xz+2 Y 2 A1 十一 十 (+1Xz+2)x+1zx+2(z+2) d 2 B -1)d 乙+2 z+1z+2)=-22 A1=2,B2=-2 2 2 2 所以 十 zz+1z+2(z+2) Y(z)=22 2、 z+1z+2(z+ y(n)=2(-1)-2(-2)+n(-2)(n≥0整理（1）式得全响应 ( ) ( )( ) ( ) 2 1 1 2 2 1 2 1 2 2 2 + + + + + = + + = z B z B z A z z z Y z ( ) ( ) ( )( ) 2 1 2 2 2 2 d d 2 1 ! 1 2 2 1 = − = −       + +  + − = z z z z z B ( ) ( ) 2 2 2 2 2 1 2 + − + + − + + = z z z z Y z 所 以 ( ) ( ) 2 2 2 2 2 1 2 + − + − + = z z z z z z Y z y(n) = 2(−1) − 2(− 2) + n(− 2) (n  0) n n n A1 = 2,B2 = −2 ( ) ( )( ) 2 1 2 2 + + = z z z Y z