1
----------
/ 2\
| x |
3*|1 + --|
\ 9 /
$$\frac{1}{3 \left(\frac{x^{2}}{9} + 1\right)}$$
-2*x
------------
2
/ 2\
| x |
27*|1 + --|
\ 9 /
$$- \frac{2 x}{27 \left(\frac{x^{2}}{9} + 1\right)^{2}}$$
/ 2 \
| 4*x |
6*|-1 + ------|
| 2|
\ 9 + x /
---------------
2
/ 2\
\9 + x /
$$\frac{6 \left(\frac{4 x^{2}}{x^{2} + 9} - 1\right)}{\left(x^{2} + 9\right)^{2}}$$