/ 2 \ \x + 1/*atan(x)
(x^2 + 1)*atan(x)
2 x + 1 ------ + 2*x*atan(x) 2 1 + x
/ x \ 2*|------ + atan(x)| | 2 | \1 + x /
/ 2 \ | 2*x | 2*|2 - ------| | 2| \ 1 + x / -------------- 2 1 + x