[tex]6561[/tex]
1) Paying attention to that we can tell that the first term is 3 and the fourth term is 81
2) The immediate consequence is to tell that the common ratio is 3 and then we can write out the following sequence:
[tex]\begin{gathered} 3,9,27,81,... \\ a_8=3^8=6561 \\ 3^4=81 \end{gathered}[/tex]
Therefore, the eighth term is 6561.
