Answer
common;
ratio;
$2$;
$5$
Work Step by Step
RECALL:
The $n^{th}$ term $a_n$ of a geometric sequence is given by the formula:
$a_n=a\cdot r^{n-1}$
where
$a$ = first term
$r$ = common ratio
This means that in the sequence $a_n=2(5)^{n-1}$,
$a=2\\
r=5$
Thus, the missing expressions in the given statement (in order) are:
common;
ratio;
$2$;
$5$