-(1 + x2)
----------
2
1 + x $$- \frac{x_{2} + 1}{x^{2} + 1}$$
2*x*(1 + x2)
------------
2
/ 2\
\1 + x / $$\frac{2 x \left(x_{2} + 1\right)}{\left(x^{2} + 1\right)^{2}}$$
/ 2 \
| 4*x |
2*(1 + x2)*|1 - ------|
| 2|
\ 1 + x /
-----------------------
2
/ 2\
\1 + x / $$\frac{2}{\left(x^{2} + 1\right)^{2}} \left(x_{2} + 1\right) \left(- \frac{4 x^{2}}{x^{2} + 1} + 1\right)$$