Question

A movie earned $40 million in its first week of release. Earnings decreased each successive week by 40%. Which recursive formula can you use to find out how much money (in millions) the movie earned n weeks after its release?

Answer 1

Since it decreases by a factor of 0.4, this is a geometric formula. The recursive geometric formula is
a subscript n=[a subscript (n-1)]*r
r is 0.4
so,
a subscript n=[a subscript (n-1)]*0.4

Answer 2

A1=40

An=(An-1)(0.6)

Explanation:

A1 = 40 because they made 40mil the first week.

An-1 means use the week before number and then you multiply by 0.6 because each week it decreases .40% so .6 is what is left. Hope that helps. I got it right.