- #1

- 678

- 4

## Homework Statement

the answer that i get is different with the answer provided , is my answer wrong ? i got ( cos(2n -1) / 2n-1 )instead of ( cos(n+1) / n+1 )

## Homework Equations

## The Attempt at a Solution

[/B]

Last edited by a moderator:

You are using an out of date browser. It may not display this or other websites correctly.

You should upgrade or use an alternative browser.

You should upgrade or use an alternative browser.

- Thread starter foo9008
- Start date

- #1

- 678

- 4

the answer that i get is different with the answer provided , is my answer wrong ? i got ( cos(2n -1) / 2n-1 )instead of ( cos(n+1) / n+1 )

[/B]

Last edited by a moderator:

- #2

vela

Staff Emeritus

Science Advisor

Homework Helper

Education Advisor

- 15,445

- 2,071

www.desmos.com is useful if you don't have access to plotting software.

- #3

- 678

- 4

I am not interested in the graph, I just wanna know the final answer....

www.desmos.com is useful if you don't have access to plotting software.

- #4

Samy_A

Science Advisor

Homework Helper

- 1,242

- 510

I actually followed vela's good advice, and the result is telling ...I am not interested in the graph, I just wanna know the final answer....

Another test you could try: what happens with the given solution (answer b) when x=π?

Last edited:

- #5

- 678

- 4

Cos(n +1 ) pi= (-1)^n.... What can we conclude from that??I actually followed vela's good advice, and the result is telling ...

Another test you could try: what happens with the given solution (answer b) when x=π?

- #6

Samy_A

Science Advisor

Homework Helper

- 1,242

- 510

No, that is not correct.Cos(n +1 ) pi= (-1)^n.... What can we conclude from that??

##\cos 2 \pi = \cos (1+1) \pi \neq {(-1)}^1##

Once you have the correct values, plug them in into the Fourier series of answer (b).

- #7

- 678

- 4

It's (-1) ^ (n +1)No, that is not correct.

##\cos 2 \pi = \cos (1+1) \pi \neq {(-1)}^1##

Once you have the correct values, plug them in into the Fourier series of answer (b).

- #8

Samy_A

Science Advisor

Homework Helper

- 1,242

- 510

Correct.It's (-1) ^ (n +1)

So what is the Fourier series of answer (b) for x=π? Does it converge? If so, to what value?

And don't forget about vela's advice: it takes 2 minutes, and yields very interesting information.

Share: