Answer:
Option E
Step-by-step explanation:
Explicit formula of a geometric sequence is,
[tex]T_n=a_1(r)^{n-1}[/tex]
Here, [tex]a_1=[/tex] First term
[tex]r=[/tex] common ratio
[tex]n=[/tex] number of terms
If, [tex]a_1=18[/tex] and [tex]a_2=9[/tex]
Common ratio of the sequence [tex]r=\frac{a_2}{a_1}[/tex]
[tex]r=\frac{9}{18}[/tex]
[tex]r=\frac{1}{2}[/tex]
By substituting these values in the formula,
[tex]T_n=18(\frac{1}{2} )^{n-1}[/tex]
Therefore, Option E is the answer.
