Question

Find a formula for the nth term of the geometric sequence. Assume the n begins with 1. a1=18, a2=9​

Answer 1

Answer:

Option E

Step-by-step explanation:

Explicit formula of a geometric sequence is,

$T_n=a_1(r)^{n-1}$

Here, $a_1=$ First term

$r=$ common ratio

$n=$ number of terms

If, $a_1=18$ and $a_2=9$

Common ratio of the sequence $r=\frac{a_2}{a_1}$

$r=\frac{9}{18}$

$r=\frac{1}{2}$

By substituting these values in the formula,

$T_n=18(\frac{1}{2} )^{n-1}$

Therefore, Option E is the answer.