| x | ||
∫ x ' (atan 1/x) dx= x atan 1/x − ∫ (−1/x2) | ||
| 1+1/x2 |
| x | 1 | 1 | ||||
= x atan 1/x + ∫ | dx = x atan | + | log (1+x2) | |||
| 1+x2 | x | 2 |
| 1 | 1 | x | ||||||||||||
=x arctg | +∫ | dx | ||||||||||||
| x |
| x2 |
| 1 | 1 | 1 | |||||||||
=x arctg | +∫ | dx | |||||||||
| x |
| x |
| 1 | x2 | dx | |||
=x arctg | +∫ | ||||
| x | x2+1 | x |
| 1 | x | |||
=x arctg | +∫ | dx | ||
| x | x2+1 |
| 1 | 1 | 2x | ||||
=x arctg | + | ∫ | dx | |||
| x | 2 | x2+1 |
| 1 | 1 | |||
=x arctg | + | ln|x2+1|+C | ||
| x | 2 |