# Need Help with simple geometric sequence

• December 7th 2008, 05:11 PM
NeedHelp18
Need Help with simple geometric sequence
In the sequence 2,6,18,..., which term is number 162?

162 = 2 x 3^(n -1)
is this how you start it?
then i get 81 = 3^(n-1)

how do i solve that without using a calculator?
• December 7th 2008, 05:26 PM
Skalkaz
simply try to find out:

3^1 = 3 < 81
3^2 = 9 < 81
3^3 = 27 < 81
etc.
• December 7th 2008, 05:30 PM
euclid2
Quote:

Originally Posted by NeedHelp18
In the sequence 2,6,18,..., which term is number 162?

162 = 2 x 3^(n -1)
is this how you start it?
then i get 81 = 3^(n-1)

how do i solve that without using a calculator?

$t_5$