2*atan(7*x)
14 --------- 2 1 + 49*x
-1372*x ------------ 2 / 2\ \1 + 49*x /
/ 2 \ | 196*x | 1372*|-1 + ---------| | 2| \ 1 + 49*x / --------------------- 2 / 2\ \1 + 49*x /