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