-6*acot(3*x)
------------
2
1 + 9*x 18*(1 + 6*x*acot(3*x))
----------------------
2
/ 2\
\1 + 9*x / / 2 \
| 9*x 36*x *acot(3*x) |
108*|- -------- - --------------- + acot(3*x)|
| 2 2 |
\ 1 + 9*x 1 + 9*x /
----------------------------------------------
2
/ 2\
\1 + 9*x /