x
----------
/ 4\
| x |
2*|1 + --|
\ 16/
$$\frac{x}{\frac{x^{4}}{8} + 2}$$
/ 4 \
| 4*x |
8*|1 - -------|
| 4|
\ 16 + x /
---------------
4
16 + x
$$\frac{1}{x^{4} + 16} \left(- \frac{32 x^{4}}{x^{4} + 16} + 8\right)$$
/ 4 \
3 | 8*x |
32*x *|-5 + -------|
| 4|
\ 16 + x /
--------------------
2
/ 4\
\16 + x /
$$\frac{32 x^{3}}{\left(x^{4} + 16\right)^{2}} \left(\frac{8 x^{4}}{x^{4} + 16} - 5\right)$$