$$\frac{6}{36 x^{2} + 1}$$
-432*x
------------
2
/ 2\
\1 + 36*x /
$$- \frac{432 x}{\left(36 x^{2} + 1\right)^{2}}$$
/ 2 \
| 144*x |
432*|-1 + ---------|
| 2|
\ 1 + 36*x /
--------------------
2
/ 2\
\1 + 36*x /
$$\frac{\frac{62208 x^{2}}{36 x^{2} + 1} - 432}{\left(36 x^{2} + 1\right)^{2}}$$