$18.$Consider

$$

$($

$$

$)$

$=$

$$

$2$

$+$

$3$

$$

$+$

$1$

$$

$($

$$

$+$

$1$

$)$

$2$

a$.$Using the final$-$value theorem, if applicable, evaluate

$$

$$

$$

$.$

b$.$Confirm the result of $($a$)$ by evaluating

lim

$$

$->$

$\backslash$infty

$$

$($

$$

$)$

$.$