# Sequences

• Jan 8th 2008, 06:44 PM
PMPowns
Sequences
OKay so i did not get this question. And i will appreciate it if someone tells me how to do it.

use the given two terms of each geometric sequences to write the expression to the nth term:

Term 4 = 45 Term 6= 180

There is some application involved and it involves linear systems.

So thanks! :)
• Jan 8th 2008, 06:51 PM
Jhevon
Quote:

Originally Posted by PMPowns
OKay so i did not get this question. And i will appreciate it if someone tells me how to do it.

use the given two terms of each geometric sequences to write the expression to the nth term:

Term 4 = 45 Term 6= 180

There is some application involved and it involves linear systems.

So thanks! :)

the nth term of a geometric series is given by: $a_n = ar^{n - 1}$ for $n \in \mathbb{N} = \{ 1,2,3,4, ... \}$

where $a$ is the first term, and $r$ is the common ratio

thus, $a_4 = ar^3 = 45$

and $a_6 = ar^5 = 180$

thus we have two simultaneous equations here, we can solve for $a$ and $r$. then we can plug that into the general form to find the nth term

can you continue?
• Jan 10th 2008, 06:13 PM
PMPowns
Thx alot, and yes i can continue. Amazing.:D