$$- \frac{9}{9 x^{2} + 1}$$
162*x
-----------
2
/ 2\
\1 + 9*x /
$$\frac{162 x}{\left(9 x^{2} + 1\right)^{2}}$$
/ 2 \
| 36*x |
162*|1 - --------|
| 2|
\ 1 + 9*x /
------------------
2
/ 2\
\1 + 9*x /
$$\frac{- \frac{5832 x^{2}}{9 x^{2} + 1} + 162}{\left(9 x^{2} + 1\right)^{2}}$$