$$\frac{4}{16 x^{2} + 1}$$
-128*x
------------
2
/ 2\
\1 + 16*x /
$$- \frac{128 x}{\left(16 x^{2} + 1\right)^{2}}$$
/ 2 \
| 64*x |
128*|-1 + ---------|
| 2|
\ 1 + 16*x /
--------------------
2
/ 2\
\1 + 16*x /
$$\frac{\frac{8192 x^{2}}{16 x^{2} + 1} - 128}{\left(16 x^{2} + 1\right)^{2}}$$