Вохху + Роску = Роскувохух!

= OY(BXX + PCK)

Да нет же. BOXXY + POCKY = LUUUUUFFFFFFF

А мне надо решить интеграл. Я забыл уже как такое решать D;

The steps once again:
1. Let u = arctan(x), change variables (and limits)
2. Use the identity 1/(1 + tan^2 u) = cos^2 u and simplify
3. Use the identity sin(u) cos(u) = sin(2u)/2
4. Integrate by parts (integrate sin(2u), differentiate the u factor)
5. Done.

http://www.wolframalpha.com/input/?i=int+%28%28xarctan+x%29%2F%281%2Bx^2%29^2%29dx+from+0+to+infinity

>>33145
LaTeX ftw:
http://www.wolframalpha.com/input/?i=int^{infty}_0+frac{x+arctan{x}}{(1%2Bx^2)^2}dx

>>33145
http://www.wolframalpha.com/input/?i=int+%28%28xarctan+x%29%2F%281%2Bx^2%29^2%29dx+from+0+to+infinity