given is

so I would like to derivate this

thus we can split it in 3 part

First wil be

the second and third one will be

finelay we get

Who can I simplify this? Greets Thanks a lot.

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- Jul 4th 2006, 06:26 AMBertDerivate.
given is

so I would like to derivate this

thus we can split it in 3 part

First wil be

the second and third one will be

finelay we get

Who can I simplify this? Greets Thanks a lot. - Jul 4th 2006, 06:56 AMSoroban
Hello, Bert!

An error in your derivative (probably a typo)

. . Otherwise, excellent work!

Quote:

Differentiate: .

You should get: .

With three (four!) different denominators, there's not much chance of simplifying.

The first term can be simplified a bit:

. . . . . but that's all . . .

- Jul 4th 2006, 08:05 AMBert
oké but the answer in my book say

What is the problem ? Greets Thanks . - Jul 4th 2006, 09:30 AMSoroban
Hello again, Bert!

Quote:

but the answer in my book say

What is the problem ?

Simple . . . the book is*wrong!*

I'm puzzled . . . you got the same wrong answer.

. . Did you just copy the book's answer and trust it to be correct?

Are you aware that the derivative of is: .

There's**no way**to get in the denominator

. . and you should know that.

- Jul 4th 2006, 09:42 AMBert
Hello

of course not I don't trust my book but the problem is if I integrate it by derive on my computer he tells me that integrate of

will be

here a screen shot of my window http://img440.imageshack.us/img440/1841/screen7oj.jpg

Greets. - Jul 4th 2006, 01:18 PMSoroban
Hello, Bert!

Quote:

The problem is if I integrate it by derive on my computer

it tells me that: .

I don't see a problem . . .

That is**not**the original function: .

- Jul 4th 2006, 10:27 PMBert
maybe the problem is that we define in an other way cotan I mean

you use arctan I think thats the function who give back an angle I don't use this.

Maybe I copy the exercise at a wrong way so let me show an excat copy.

http://img133.imageshack.us/img133/1...oblemee1sr.jpg

Greets Tanks a lot. - Jul 5th 2006, 06:00 AMSoroban
Hello, Bert!

Sheesh! . . .**That**explains our different answers . . .

The function is: .

Your notation was incorrect and misleading . . .

We know that: . means

. . but and should be written******

The symbols .

. . are used to signify the*inverse tangent of*

That is, does not mean

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

******

I don't understand why you replaced with its reciprocal.

. . There is a*formula*: .

- Jul 5th 2006, 08:08 AMBert
this will be the problem I think The matter is that ther are different notations in different language area.

So let we work with the original copy of my book.

Where do I miss then in my answer?

Greets Thanks. - Jul 5th 2006, 09:46 AMSoroban
Hello again, Bert!

I got it! . . .

They did more simplifying than I thought humanly possible!

We have: .

Then: .

I've already shown that the first fraction can be simplfied.

. . So we have: .

The second fraction is: .

. . .

The third term is: .

. . So we have: .

Therefore: .*. . . ta-DAA!*

- Jul 6th 2006, 12:08 AMBert
thank you very much I see.

Greets.