2 atan (7*x)
d / 2 \ --\atan (7*x)/ dx
14*atan(7*x) ------------ 2 1 + 49*x
98*(1 - 14*x*atan(7*x)) ----------------------- 2 / 2\ \1 + 49*x /
/ 2 \ | 21*x 196*x *atan(7*x)| 1372*|-atan(7*x) - --------- + ----------------| | 2 2 | \ 1 + 49*x 1 + 49*x / ------------------------------------------------ 2 / 2\ \1 + 49*x /