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