Question

Calc II - NEED HELP!

Find the length of the curve for the interval:

Answer 1

Length = Integral (sqrt (1+(y')^2),x,a,b)

Answer 2

y = ln(e^t+1)-ln(e^t-1)
y' = e^t/(e^t+1) - e^t/(e^t-1)

Answer 3

http://tutorial.math.lamar.edu/Classes/CalcII/ArcLength.aspx

Answer 4

(y')^2 = (e^t/(e^t+1) - e^t/(e^t-1))^2, oh my that is a pain to integrate!!

Answer 5

Do you just want the answer or do you want to try and understand the solution? cuz in the previous case, it seemed like you couldn't care less about the solution.

Answer 6

I can just integrate and differentiate and evaluate this whole thing on a calculator right now.

Answer 7

well, at the moment the answer is preferred, and then I can take my time and 'reverse engineer' it later tonight

Answer 8

didn't I just post the options and the question?

Answer 9

-((e^(2 t)-1) sqrt((e^(2 t)+1)^2/(e^(2 t)-1)^2) (t-log(1-e^(2 t))))/(e^(2 t)+1)
evaluate from e to f

Answer 10

Sorry if I'm being difficult, what I mean is, I need the answer sooner, but all work done is greatly appreciated, I still have to learn this

Answer 11

For these kinds of problems (if I were fresh on integrals lol), I'd just write out the solution and scan it in if someone really needed the steps. B/c bahrom's right. It takes waay too much time to type it out.

Answer 12

I just like watching people work difficult problems.

Answer 13

lol, well, I'm kinda behind in my studies atm, and thats why I'm in a rush, but I need all the steps aswell, if that makes any sence @bahrom7893 and @brinethery

Answer 14

@bahrom7893 could you finish the problem please? I really hope I'm not sounding like one of those people who want the answer and go, I do need all the assistance I can get

Answer 15

well, actually you do. And that's like one of the reasons a couple of really good answerers left the website, anyway i'll finish this on paper.. hold on

Answer 16

I'm sorry that I do, I really wasn't sure of a better say to say, I'm behind on my work, and I help plus answers

Answer 17

You can leave this tab open while you help others on here.

Answer 18

were there other conditions? such as f = something?

Answer 19

Bahram, what did you get for your derivative? I tried working the first part of the problem on scratch paper. Is it close to what you got?

Answer 20

its says that e is less then or equal to t which is is less then or equal to f

Answer 21

any progress?

Answer 22

brine, I just triple checked my derivative, it is:
-2e^t/(e^(2t) - 1)

Answer 23

working on the integral now...

Answer 24

ok

Answer 25

This is a nasty problem, so I am just a spectator for now lol.

Answer 26

im not getting any of those answers.

Answer 27

Neither is wolframalpha..

Answer 28

Thats not good,

Answer 29

ughhh hold on... im a freakin math major after all...

Answer 30

lol

Answer 31

Okay, my derivative was correct:
http://www.wolframalpha.com/input/?i=differentiate+%28ln%28%28e%5Et%2B1%29%2F%28e%5Et-1%29%29%2Ct%29
I got the same thing.

Answer 32

Not to make matter worse, but I have to submit in 10 min

Answer 33

y'^2 = 4e^(2t)/(e^(2t)-1)^2
http://www.wolframalpha.com/input/?i=%28+-%282+e%5Et%29%2F%28e%5E%282+t%29-1%29%29%5E2
wolf agrees.

Answer 34

How many more problems?

Answer 35

well there are 3 others, but they count for less points

Answer 36

its is 15, they are 5

Answer 37

Post the on the left, what are u waiting for? There are other answerers too.

Answer 38

My final integral is: ln(1-e^(2t)) - t

Answer 39

thats not an option though

Answer 40

i know..
i get to: