Q$8.$ Which of the following functions are negligible? Justify your answer in each case.

$($a$)$ f$($n$)=1/$log$($n$)$

$($b$)$ f$($n$)=1/(2$n$)$

$($c$)$ f$($n$)=1/($n$^2)$

$($d$)$ f$($n$)=$ n$/($n$!)$