Question

What is the 10th term of the sequence 81, 27, 9, …

Answer 1

Is this geometric or arithmetic?

Answer 2

It didn't say.

Answer 3

@stamp

Answer 4

if it has common ratio then it is geometric sequence while if it has common difference it is arithmetic sequence

Answer 5

I forgot how you do these, you've got to like fine out what the one before the first one would have been and then go from there

Answer 6

@Kayy_Drizzyy It does not tell you, that is why I am asking you. Did you miss lecture? Surely you have been over how to differ from a geometric or an arithmetic sequence. If not, your teacher is doing you injustice.

Answer 7

What it says above is what my question is asking me.

Answer 8

Kayy, you need to find out which one it is, we know it doesn't tell you

Answer 9

I know what your question is asking you. And I know what you are asking me, which is to solve it for you. But I want to solve this together, which means I ask you questions after you ask me yours.

Is this sequence arithmetic or geometric? People in this thread have already given you hints as to how to tell which it is.

Answer 10

81/3 = 27 27/3 = 9
Do that a few more times.................. its going to get negative.

Answer 11

@NeedMathHelpNoa False, it is not going to get negative. It is merely going to get more and more fractional. And while it is extremely small fractions, they stay positive (aka > 0).

Answer 12

It's impossible to go negative no matter how many times you do that, needmathhelpnoa

Answer 13

What do i do ? Sorry you guys i'm just confused

Answer 14

Well, that's just it... what ARE you doing to the number?
You just keep dividing it by 3, right? :D

Answer 15

right

Answer 16

Well, that's the bad way to do it, there is a formula. @PeterPan

Answer 17

but its asking what would you 10th term be

Answer 18

@Kayy_Drizzyy Arithmetic sequence:\[1, \ 3,\ 5,\ 7\]Notice how I add 2 everytime. This is arithmetic.\[1,\ 2,\ 4,\ 8\]This is geometric. I am not adding or subtracting the same number every time, as 1 to 2 is +1, while 2 to 4 is +2. So what is the pattern? It is geometric. I am multiplying by 2 to get my next sequence.

So in your problem, you are not adding or subtracting the same number every time because clearly this is not the case. So this is NOT an arithmetic sequence, but if you can find a common multiplying or dividing factor you can identify it as geometric. As others have mentioned, you are dividing by 3 (or multiplying by 1/3) each time to obtain your next time.

Do you recall the formula for finding the nth term of a geometric sequence? Unless you are skipping lecture, you should have this formula on deck or somewhere in your notes.

Answer 19

Thanks.

Answer 20

I'm stuck between 2 answers on my answer choice. I need help to figure out which one is it.

Answer 21

You need to find the so-called 0 term. To do this you multiply by 3 instead of dividing by 3 and you get 243. You take 243 and multiply it by your pattern which in this case is dividing by three so multiplying by 1/3. 243x1/3^nth power (where n is how far along you are and you are trying to find the 10th one so 243x1/3^10

Answer 22

Which I'm going to go ahead and tell you is 0.0041

Answer 23

243 was in my answer choice and thats one of them that i thought was it, but i wanted to make sure that 243 was my final CORRECT answer.

Answer 24

243 is not your answer

Answer 25

0.0041 is

Answer 26

1/243 ? It's all by fractions. for explain 1/my answer

Answer 27

example*

Answer 28

What are all of the possible answers? (ie a: 243: b: 234 etc etc)

Answer 29

A) 1/729
B) 1/243
C) 1/81
D) 1/810

Answer 30

B, 1/243

Answer 31

You told me it was wrong. Are you sure ?

Answer 32

Sorry, I couldn't help sooner than I did, I had to think about it for a while because I learned this in 6th grade algebra 1 (I'm in 9th grade now)

Answer 33

I thought you said only 243 earlier

Answer 34

Well anyways thank you for your help.

Answer 35

You're welcome, goodluck. Message me if you need anything.

Answer 36

Will do.