$$\frac{1}{2} + \frac{1}{x^{2} + 1}$$
-2*x
---------
2
/ 2\
\1 + x /
$$- \frac{2 x}{\left(x^{2} + 1\right)^{2}}$$
/ 2 \
| 4*x |
2*|-1 + ------|
| 2|
\ 1 + x /
---------------
2
/ 2\
\1 + x /
$$\frac{\frac{8 x^{2}}{x^{2} + 1} - 2}{\left(x^{2} + 1\right)^{2}}$$