Question

Find an explicit rule for the nth term of a geometric sequence where the second and fifth terms are 20 and 2500, respectively.

Answer 1

2500/20 = 125
125 = 5^3
an fifth term / second term = r^3 where r is the common ratio
so r^3 =5^3
hence r= 5
and the first term is 20/5=4
so nth term = 4 * 5^(n-1)

Answer 2

ahhh okay. That makes sense :) thanks

Answer 3

yw