#### Answer

$a_1 \cdot r^{n-1}$;
$\text{first term}$;
$\text{common ratio}$

#### Work Step by Step

RECALL:
The $n^{th}$ term ($a_n$) of a geometric sequence can be found using the formula
$a_n=a^1 \cdot r^{n-1}$
where
r = common ratio
$a_1$ = first term
Thus, the missing expressions in the given statements are $\underline{a_1 \cdot r^{n-1}}$; $\underline{\text{first term}}$; and $\underline{\text{common ratio}}$, respectively.