Найти производную 7/ctg в кубе 2х

Найдем производную функции 7/ctg ^ 3 (2 * х).y \' = (7/ctg ^ 3 (2 * х)) \' = (7 \' * ctg ^ 3 (2 * х) - (ctg ^ 3 (2 * х)) \' * 7)/(ctg ^ 6 (2 * x)) = (0 * ctg ^ 3 (2 * х) - (ctg ^ 3 (2 * х)) \' * 7)/(ctg ^ 6 (2 * x)) = - (ctg ^ 3 (2 * х) \' * 7/(ctg ^ 6 (2 * x)) = - 3 * ctg ^ 2 (2 * x) * 7 * ctg \' (2 * x)/(ctg ^ 6 (2 * x)) = - 21 * ctg ^ 2 (2 * x) * ctg \' (2 * x)/(ctg ^ 6 (2 * x)) = - 21 * ctg ^ 2 (2 * x) * (- 1/sin ^ 2 (2 * x)) * (2 * x) \' /(ctg ^ 6 (2 * x)) = 42 * ctg ^ 2 (2 * x) * (1/sin ^ 2 (2 * x))/(ctg ^ 6 (2 * x)) = 42 * cos ^ 2 (2 * x)/sin ^ 2 (2 * x) * (1/sin ^ 2 (2 * x))/(ctg ^ 6 (2 * x)) = (42 * cos ^ 2 (2 * x)/sin ^ 4 (2 * x))/(ctg ^ 6 (2 * x)) = (42 * cos ^ 2 (2 * x)/sin ^ 4 (2 * x))/(sin ^ 6 (2 * x)/cos ^ 6 (2 * x)) = (42 * cos ^ 2 (2 * x)/sin ^ 4 (2 * x)) * (cos ^ 6 (2 * x)/sin ^ 6 (2 * x))= 42 * cos ^ 8 (2 * x)/sin ^ 10 (2 * x).