Hi,
I got stuck while trying to calculate the third derivative for arctan.
The second derivative for arctan is
No problem. Then i try to rewrite it as: and use the product rule. This is what i end up with:
which can be rearanged into:
and it's wrong. What am i doing wrong?
Ok, thanks guys. But are you sure thats correct?
The key says
look:
Arctan @ pici.se