I am trying to find the derivative of a pretty simple problem but I just can not force the answer to match the one provided by the book.
$ - \frac {(1+x^2)^\frac{1}{2}}{x}$
I mean it is a very simple problem and I get
$\frac {x^2 (1+x^2)^{-.5} - (1+x^2)^.5} {x^2}$