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