3*atan(3*x)
--------------------
/ 2\
\1 + 9*x /*atan(3*x)
$$\frac{3 \operatorname{atan}{\left(3 x \right)}}{\left(9 x^{2} + 1\right) \operatorname{atan}{\left(3 x \right)}}$$
-54*x
-----------
2
/ 2\
\1 + 9*x /
$$- \frac{54 x}{\left(9 x^{2} + 1\right)^{2}}$$
/ 2 \
| 36*x |
54*|-1 + --------|
| 2|
\ 1 + 9*x /
------------------
2
/ 2\
\1 + 9*x /
$$\frac{54 \left(\frac{36 x^{2}}{9 x^{2} + 1} - 1\right)}{\left(9 x^{2} + 1\right)^{2}}$$