$3\mathrm{.}24$ A system is characterized by a transfer function given by H$($s$)=18$s$+10$ s $2+6$s$+5.$ Determine the output response y$($t$),$ if the input excitation is given by the following: $*($a$)$ x$1($t$)=$ u$($t$)($b$)$ x$2($t$)=2$t u$($t$)($c$)$ x$3($t$)=2$e $4$t u$($t$)($d$)$ x$4($t$)=[4$ cos$(4$t$)]$ u$($t$)$