The first derivative
[src]
$$- \frac{6 x}{9 x^{4} + 1}$$
The second derivative
[src]
/ 4 \
| 36*x |
6*|-1 + --------|
| 4|
\ 1 + 9*x /
-----------------
4
1 + 9*x
$$\frac{6 \cdot \left(\frac{36 x^{4}}{9 x^{4} + 1} - 1\right)}{9 x^{4} + 1}$$
The third derivative
[src]
/ 4 \
3 | 72*x |
216*x *|5 - --------|
| 4|
\ 1 + 9*x /
---------------------
2
/ 4\
\1 + 9*x /
$$\frac{216 x^{3} \left(- \frac{72 x^{4}}{9 x^{4} + 1} + 5\right)}{\left(9 x^{4} + 1\right)^{2}}$$