Find an explicit formula for the sequence 30\,,\,150\,,\,750\,,\,,150,750,, space, comma, space, 150, space, comma, space, 750, space, comma, space, 3750, comma, point, point, point.

The series shown is an geometric series and the explicit formula is given by:
an=ar^(n-1)
where
a=first term
n=number of terms
r=common ratio
from the sequence:
a=30
r=5
thus the explicit formula will be:
an=30(5)^(n-1)
hence the answer is:
an=30(5)^(n-1)

Ibelieve it's a. 2.2 - x = -10.85 (plz tell me if it's right : ) )