# Sequences and Series - summation notation

• May 3rd 2010, 12:42 PM
danield3
Sequences and Series - summation notation
1. Determine the approximate value of Attachment 16675

2. Evaluate Attachment 16676

3. Find the value of the 8th term of the series Attachment 16677 9(4)j - 6.
• May 3rd 2010, 05:51 PM
mr fantastic
Quote:

Originally Posted by danield3
1. Determine the approximate value of Attachment 16675

2. Evaluate Attachment 16676

3. Find the value of the 8th term of the series Attachment 16677 9(4)j - 6.

Do you understand what $\displaystyle \sum$ means? What have you tried and where are you stuck?
• May 3rd 2010, 09:03 PM
danield3
Quote:

Originally Posted by mr fantastic
Do you understand what $\displaystyle \sum$ means? What have you tried and where are you stuck?

I do not know how to do it. Can you help me.
• May 4th 2010, 02:22 AM
mr fantastic
Quote:

Originally Posted by danield3
I do not know how to do it. Can you help me.

It would help if you had answered the two questions I asked you (or at leats the first question).

Q1 By definition: $\displaystyle \sum_2^8 3^{k-1} = 3^1 + 3^2 + 3^3 + 3^4 + 3^5 + 3^6 + 3^7 = .....$ and you can go to a calculator and evaluate. Alternatively, if you've been taught about geometric series, you can use the usual formula to evaluate it (a = 3, r = 3, n = 7).

The other two are left for you to attempt. Please show what you have done. Say where you are stuck.