HELP does anyone know this?

Identify a1 and r for the geometric sequence an= -256(-1/4) n-1

The radius of the earth is two times the radius of the moon. what fraction of the volume of the earth is the volume of the moon?

Asales representative from a local radio station is trying to convince the owner of a small fitness club to advertise on her station. the representative says that if the owner begins advertising on the station today, the club's total number of members will grow exponentially each month. she uses the given expression to model the number of club members, in hundreds, after advertising for t months.