Question

The first and seventh terms of a sequence are each 10. Starting with the third term, each term is the sum of the previous two terms. What is the fifth term?

Answer 1

Pleease help me!

Answer 2

@Hero

Answer 3

@phi

Answer 4

@Juliette32801

Answer 5

Anyone???

Answer 6

That one is difficult, and I dont really have an idea.. Im sorry but good luck (:

Answer 7

Thanks anyways:)

Answer 8

yw (:

Answer 9

Anyone have an idea? Hero?

Answer 10

So basically, what you have is

\(10,a_2, a_3, a_4, a_5, a_6, 10\)

And starting with the third term, each term is the sum of the previous two terms so:

\(10,a_2, (10 + a_2), (2a_2 + 10), (3a_2 + 20), (5a_2 + 30), 10\)

Answer 11

Now use formula for nth term of a sequence

Answer 12

That's right....

Answer 13

Well, I don't think it would be 2a2 +10, it would just be a2 +10

Answer 14

and it probably isn't + 10 each time, right?

Answer 15

"Each term is the sum of the previous two terms"

Answer 16

\(a_2 + a_2 + 10 = 2a_2 + 10\)

Answer 17

Because \(a_2 + a_2 = 2a_2\)

Answer 18

but the third term would be a2 +10

Answer 19

That's what I have bro

Answer 20

Do you not see?

Answer 21

10 is the first term
\(a_2\) is the second term
\(a_2 + 10\) is the third

Answer 22

you have 2a2 +10

Answer 23

Look at it again bro.

Answer 24

so 2 times a2+10

Answer 25

oh never mind

Answer 26

If you don't see that I have \(a_2 + 10\) for the third term, I cannot help you.

Answer 27

I do see

Answer 28

well the formula is:

tn=t1+(n-1)d

and I understand the formula, but what's the difference(d)?

Answer 29

I already said I understand that bro:)

Answer 30

My problem is the formula:

well the formula is:

tn=t1+(n-1)d

and I understand the formula, but what's the difference(d)?

Answer 31

You have to solve for it

Answer 32

ok

Answer 33

let me try

Answer 34

You're supposed to be brain storming with me bro

Answer 35

Everything makes sense except for the last term now

Answer 36

Why did you stop communicating with me? Now is not the time to bail out on me.

Answer 37

Okay, I have it. Thanks for the help bro.

Answer 38

We have to solve

\(8a_2 + 50 = 10\)

Answer 39

Since 10 is supposed to be the sum of the previous two terms. We don't need to use the other formula

Answer 40

So \(a_2 = -5\)

Answer 41

So the sequence is 10,-5, 5,-.5,5,10

Answer 42

I'm pretty sure I lost you bro since you are not communicating with me.

Answer 43

@me1567 are you there?

Answer 44

oh god I had some computer problems, and I didn't have time to tell you I wasn't there!

Answer 45

I see. It is finished...

Answer 46

Glad you were still logged in so I could tell you...
I just finished reading all your replies...wow

Answer 47

Did you understand it?

Answer 48

yup:) Thanks for explaining it so well...