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