Answer:
[tex]\text{B. }a_n=625(0.2)^{n-1}\quad\text{for $n>1$}\\625,125,25,5,1[/tex]
Step-by-step explanation:
The explicit formula for a geometric sequence with first term a1 and common ratio r is ...
[tex]a_n=a_1\cdot r^{n-1}[/tex]
In this problem, you are given a1=625 and r=0.2. Filling in those values gives the explicit formula ...
[tex]a_n=625(0.2)^{n-1}[/tex]
You can either evaluate this function for values of n = 1 through 5, or you can multiply each term by the common ratio to get the next.
a1 = 625
a2 = 625·0.2 = 125
a3 = 125·0.2 = 25
a4 = 25·0.2 = 5
a5 = 5·0.2 = 1
