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