# Thread: Help with series...

1. ## Help with series...

From the series:16, 14, 12, 10......

(a) Find Tn
(b) Find Sn
(c) Find the sum of the first 12 terms.

I am not sure how to do this as I was not given any information in class. Also if you know any articles on this, could you please post a link.

THANKS

2. Originally Posted by holmesb
From the series:16, 14, 12, 10......

(a) Find Tn
(b) Find Sn
(c) Find the sum of the first 12 terms.

I am not sure how to do this as I was not given any information in class. Also if you know any articles on this, could you please post a link.

THANKS
This seems like an arithmetic sequence:
$t_n = 18 - 2n$

The sum of term is,
$18 - 2(1) + 18 - 2(2) + ... + 18 - 2(n)$
Rewrite,
$\underbrace{(18+18+...+18)}_n - 2(1+2+...+n)$
$18 n - 2\cdot \frac{n(n+1)}{2} \Rightarrow 18 n - n^2 - n = 17n - n^2$

3. Hello, holmesb!

From the series: 16, 14, 12, 10, ...

(a) Find $T_n$
(b) Find $S_n$
(c) Find the sum of the first 12 terms.

I am not sure how to do this as I was not given any information in class.

You were given no information ???
. . Then you don't know that $T_n$ means . . . or $S_n$

Better wait until your teacher explains all this . . .