P$-6\mathrm{.}5$ An LTI filter is described by the difference equation y$[$n$]=3$x$[$n$]+2$x$[$n$1]+$x$[$n$2]($a$)$ Obtain an expression for the frequency response of this system. $($b$)$ Determine the output when the input is x$[$n$]=1+2$cos$(0\mathrm{.}5$n$+0\mathrm{.}1$$)$ for $$