Question

Write the next explicit form of this sequence, given a1 = 20 and r= 0.5 (1/2) and find n=15.

Answer 1

Given the first term, a1=20

Common ratio, r=0.5*1/2=0.25

A geometric sequence is represented by the following expression:

`\begin{gathered} a_n=ar^(n-1) \\ \end{gathered}`

We want to find the 15th term:

`\begin{gathered} a_(15)=20(0.25)^(15-1) \\ a_(15)=7.45*10^(-8) \end{gathered}`