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# Quick trig differentiation answer check watch

1. Question from book

Given that y=arctan(x-1/x) show that

dy/dx = (x+1)/(x^4-x^2+1)

I don't get that - I get

dy/dx = (x^2+1)/(x^4-x^2+1)

Can someone do an answer check for me, I've tried it a couple of different methods and my answer differs from the book
2. so annoying, is that arctan((x-1)/x) or arctan(x -1/x)?
4. (Original post by Kolya)
did you just delete your post then repost the same post?
5. (Original post by Totally Tom)
did you just delete your post then repost the same post?
I thought I might have made a mistake so deleted while I checked, but it turned out I was correct all along.
6. thanks for that - i need another answer check:

integrate 1/(x^2)-4

I've got -1/2artanh(1/2)x

The book has something with ln in it - I'm guessin they're way off
7. can you make it clearer what the actual integral is?

is it
Unparseable or potentially dangerous latex formula. Error 4: no dvi output from LaTeX. It is likely that your formula contains syntax errors or worse.
\displaystyle\int{\frac{1}{x^2-4}
?

if so, I would use partial fractions. then it will have something with ln in it.
8. Yes, it is. I can see why using partial fractions would help, but surely I can also do:

=

and then use a standard result to integrate into

9. (Original post by studienka)
Yes, it is. I can see why using partial fractions would help, but surely I can also do:

=

and then use a standard result to integrate into

they're equivalent.

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