# Tutor.com Sequences and Series Session

##### Apr. 13, 2013

Session Transcript - Math - Algebra II, 3/5/2013 8:25PM - Tutor.comSession Date: 3/5/2013 8:25PM
Length: 17.3 minute(s)
Subject: Math - Algebra II

System Message
[00:00:00] *** Please note: All sessions are recorded for quality control. ***

Brinda (Customer)
[00:00:00] 8,17,26,35,44... The first 5 terms in a sequence are shown above. Each term after the first is found by adding nine to the term immediately preceding it. Which term in this sequence is equal to 8+(26-1)9? A. The 8th B. The 9th C. The 25th D. The 26th E. The 27th I am a freshman in high school. I can understand things pretty well, but please be patient with me.

Carl T (Tutor)
[00:00:11] Welcome to Tutor.com ! Let's get started.

Brinda (Customer)
[00:00:15] ok.

Carl T (Tutor)
[00:01:17] Looks like you have a good sequence problem here to work on today. Do you know the type of sequence that this problem involves (arithmetic or geometric)?

Brinda (Customer)
[00:01:38] I'm thinking arithmetic.

Carl T (Tutor)
[00:01:48] That is correct. Do you know why?

Brinda (Customer)
[00:02:22] Because it says that each term is found by adding 9 to the preeding term.

Carl T (Tutor)
[00:02:32] Good job. That is correct.
[00:02:55] For this question we want to know what term is represented by the statement 8+(26-1)9.

Brinda (Customer)
[00:03:09] Right.

Carl T (Tutor)
[00:03:27] Do you recall an arithmetic formula that represents this statement?

Brinda (Customer)
[00:03:48] Um... no, not really.

Carl T (Tutor)
[00:04:00] No worries.
[00:04:33] This statement comes from the formula used to find a specific term of an arithmetic sequence.
[00:05:13] Have you seen that formula before?

Brinda (Customer)
[00:05:20] no, never.

Carl T (Tutor)
[00:05:56] That's probably why you aren't sure about the problem. Let me explain the parts of this formula to you and then I bet you will be able to answer your question.

Brinda (Customer)
[00:06:08] ok.

Carl T (Tutor)
[00:06:56] The a n represents the term of of a sequence. So the 7th term of a sequence would be identified as a 7 .
[00:07:15] The 12th term would be a 12 .
[00:07:29] Does that part make sense so far?

Brinda (Customer)
[00:07:37] Yes. Perfect sense.

Carl T (Tutor)
[00:08:01] Good deal. What do you think a 1 represents on the right side of the =?

Brinda (Customer)
[00:08:20] the first term in the sequence, right?

Carl T (Tutor)
[00:08:28] Good job. That is correct.
[00:09:21] Next we see (n-1). The n represents the term number of the sequence. So if we are looking for the 8th term in a sequence, we would sub in 8 for n.

Brinda (Customer)
[00:09:45] ok.
[00:09:47] oh!!!
[00:09:52] I think I got the answer.

Carl T (Tutor)
[00:10:01] What do you think it is?

Brinda (Customer)
[00:10:14] the 26th term?

Carl T (Tutor)
[00:10:18] You got it!

Brinda (Customer)
[00:10:28] Wow. That was so simple!

Carl T (Tutor)
[00:10:47] It is simple once you know the formula.

Brinda (Customer)
[00:10:55] Yeah.

Carl T (Tutor)
[00:11:07] For future reference the d is the common difference. The amount we add each time.
[00:11:25] Do you have any questions about anything we went over today?

Brinda (Customer)
[00:12:23] what does the common difference mean? Is that where the 9 comes in?

Carl T (Tutor)
[00:13:23] Yes. For your sequence, if we subtract two consecutive terms (17-8 for example), then we get 9 every time.
[00:13:44] That is because 9 is the amount being added to each value to get the next term in the sequence.

Brinda (Customer)
[00:14:11] Right... okay. Alright. It all makes sense to me now.

Carl T (Tutor)
[00:14:26] Excellent. Do you have any other questions?
[00:15:59] I'm working on this...

Brinda (Customer)
[00:16:19] Nothing else.
[00:16:24] Thank you.

Carl T (Tutor)
[00:16:38] You are very welcome. I've enjoyed working with you today.
[00:16:44] Thanks for using Tutor.com.Â Please fill out the survey as you leave so we can learn how we can better help you in the future!Â

Brinda (Customer)
[00:16:52] Sure thing.

Carl T (Tutor)
[00:16:59] Bye.

Brinda (Customer)
[00:17:09] See you.