# Can someone help with this?

May 10, 2018

#### Explanation:

Because geometric sequence has the formula as
${a}_{n} = {a}_{0} {r}^{n - 1}$ where ${a}_{0}$ is the first term and $r$ is the ratio.

In our case ${a}_{0} = 1$

r is the ratio which can be obtained ${a}_{2} / {a}_{1} = 3$ and in general

${a}_{n} / {a}_{n - 1} = r$ So in your question it is 3/1So r=3
While n is the number of term
If they would have said T9
This means n=9
Thus your term is ${a}_{n} = 1 \cdot {3}^{n - 1}$