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