$9\mathrm{.}4-3$ Consider a OT system with input x $[11]$and out

puty$[11$I described by the difference equation

$4$y$[11+$ I $\}+$y$[11-$ I $]=8$xl$11+$I$]+8$x$[11]$

$($a$)$ What is the order of this system?

$($b$)$ Determine the characteristic mode$($s$)$ of

the system.

$($c$)$ Determine a closed$-$form expression for

the system's impulse response h$[11].$