$(8$ Points$)$ Find the infimum, supremum, maximum, and minimum of each of the sets

below, if they exist. If the set is unbounded above or below use $+-\backslash$infty as the value for

the infimum or supremum as is appropriate. If a value does not exist, write DNE.

$($a$)$ A$=[0,1]\backslash$cup $(\backslash$sqrt$(2),5]\backslash$cup $[6,7)$

$($b$)$ B$=\{4(-1)^($n$)+(1)/($n$)$:ninN$\}$