First term (a1) is -1
recursive formula goes like this
is the nth term
is the term before that
we normally have
we see each term is multipying by -3 to get next one
so that would be
where a1=-1
the 3rd option is correct except that it is the explicit formula
so answer is 2nd one
recursive formula goes like this
we normally have
we see each term is multipying by -3 to get next one
so that would be
the 3rd option is correct except that it is the explicit formula
so answer is 2nd one