# Thread: find the derivative of the function..

1. ## find the derivative of the function..

ok so here is the problem http://www.flickr.com/photos/23409594@N02/4277189853/ needless to say my answer is not what the book has and i would like to know why. for starts their answer has a natural log in it? i separated the natural log in the problem and took the derivative using the product rule. so where did i go wrong? well take a look at the problem and tell me what you think. sorry its problem number 55.

2. Originally Posted by slapmaxwell1
ok so here is the problem homework problem on Flickr - Photo Sharing! needless to say my answer is not what the book has and i would like to know why. for starts their answer has a natural log in it? i separated the natural log in the problem and took the derivative using the product rule. so where did i go wrong? well take a look at the problem and tell me what you think. sorry its problem number 55.

show your attempt so maybe someone can spot any mistake(s).

3. ok here is my work, it is broken into two parts, the paper i was using was a little long..anways here it is..my final answer was -4/(stuff) you will see it on the paper. thanks in advance.. problem number 55 001 on Flickr - Photo Sharing! and here is part 2 of the same problem problem number 55 002 on Flickr - Photo Sharing!

4. $y = \frac{1}{2}\left(\frac{1}{2} \ln{\frac{x+1}{x-1}} + \arctan{x}\right)$

$y = \frac{1}{2}\left[\frac{1}{2} \ln(x+1) - \frac{1}{2}\ln(x-1) + \arctan{x}\right]$

$y' = \frac{1}{2}\left[\frac{1}{2(x+1)} - \frac{1}{2(x-1)} + \frac{1}{1+x^2}\right]$

5. Originally Posted by skeeter
$y = \frac{1}{2}\left(\frac{1}{2} \ln{\frac{x+1}{x-1}} + \arctan{x}\right)$

$y = \frac{1}{2}\left[\frac{1}{2} \ln(x+1) - \frac{1}{2}\ln(x-1) + \arctan{x}\right]$

$y' = \frac{1}{2}\left[\frac{1}{2(x+1)} - \frac{1}{2(x-1)} + \frac{1}{1+x^2}\right]$

yes that is essentially what i was doing..i think i got carried away towards the end as i was trying to match what the back of the book's answer. thanks again!