An LTI system has the transfer function : H$($z$)=$ z$/($z$-1)($z$-2).$ Compute the following: $($a$)$ the zeros and poles. is the system stable? $($b$)$ the difference equation. $($c$)$ the response to input x$[$n$]=\{2,-6,4\}.($d$)$ the response x$[$n$]=\{1,-1\}.($e$)$ the impulse responseh$[$n$].$