$7\mathrm{.}25$ An LTI system has the transfer function H$($z$)=($z $1)($z $6)($z $2)($z $3).$ Compute the following: $($a$)$ The zeros and poles. Is the system stable? $($b$)$ The difference equation. $($c$)$ The response to input x$[$n$]=\{1,5,6\}.($d$)$ The impulse response h$[$n$].7\mathrm{.}26$ An LTI system has the transf