Question

Two terms in a geometric sequence are a5=15 and a6=1. What is the recursive rule that describes the sequence?

Answer 1

Rule = 759375(1/15)^(n-1)

Where n represent the number of term

Explanation:

a5= ar^4= 15

a6= ar^5= 1

ar^4=15... Equation 1

ar^5=1.... Equation 2

Dividing equation 2 by equation 1

r= 1/15

For the value of a

ar^5=1

a(1/15)^5= 1

a(1/759375)= 1

a= 759375

Rule = 759375(1/15)^(n-1)

Where n represent the number of term