$$\frac{x}{\frac{x^{4}}{4} + 1}$$
/ 4 \
| 4*x |
4*|1 - ------|
| 4|
\ 4 + x /
--------------
4
4 + x
$$\frac{1}{x^{4} + 4} \left(- \frac{16 x^{4}}{x^{4} + 4} + 4\right)$$
/ 4 \
3 | 8*x |
16*x *|-5 + ------|
| 4|
\ 4 + x /
-------------------
2
/ 4\
\4 + x /
$$\frac{16 x^{3}}{\left(x^{4} + 4\right)^{2}} \left(\frac{8 x^{4}}{x^{4} + 4} - 5\right)$$