$\frac{2}{5},\frac{8}{25},\frac{26}{125},\frac{80}{625},$dots

$4$

$5$pts$.)$

$a_n=(-1{)}^n\frac{(n-2)!}{n!}$

$5$pts$.)$

Determine whether the sequence increases or decreases $($explain$)$ and find the UB and LB if possible.

$(8$pts$.)$

$a_n=\frac{n}{2^{n+2}}$

Increasing

Decreasing

LB $q,$

$$

UB