Answer
$a_n=4(-2)^{n-1}$;$n=1,2,3,4,...$
Work Step by Step
Since, we have $4,-8,16,-32....$
This represents a geometric progression sequence with initial term $a=4$ and common ratio, $r=-2$
The n-the term can be represented as:
$a_n=ar^{n-1}$
and
$a_n=4(-2)^{n-1}$;$n=1,2,3,4,...$
