10*atan(5*x)
------------
2
1 + 25*x 50*(1 - 10*x*atan(5*x))
-----------------------
2
/ 2\
\1 + 25*x / / 2 \
| 15*x 100*x *atan(5*x)|
500*|-atan(5*x) - --------- + ----------------|
| 2 2 |
\ 1 + 25*x 1 + 25*x /
-----------------------------------------------
2
/ 2\
\1 + 25*x /