$$\frac{3 x^{2}}{x^{6} + 1}$$
/ 6 \
| 3*x |
6*x*|1 - ------|
| 6|
\ 1 + x /
----------------
6
1 + x
$$\frac{6 x}{x^{6} + 1} \left(- \frac{3 x^{6}}{x^{6} + 1} + 1\right)$$
/ 6 12 \
| 27*x 36*x |
6*|1 - ------ + ---------|
| 6 2|
| 1 + x / 6\ |
\ \1 + x / /
--------------------------
6
1 + x
$$\frac{1}{x^{6} + 1} \left(\frac{216 x^{12}}{\left(x^{6} + 1\right)^{2}} - \frac{162 x^{6}}{x^{6} + 1} + 6\right)$$