помогите найти производную функции
y = ln^3 (sin (7x)) Здесь 4 функции одна в другой: y1 = 7x; y2 = sin (y1); y3 = ln (y2); y4 = y3^3 y' = 3*y3^2*(y3)' = 3*y3^2*(1/y2)*(y2)' = 3*y3^2*(1/y2)*cos (y1)*(y1)' y' = 3*ln^2 (sin (7x))*(1/sin (7x))*cos (7x)*7 = 21*ln^2 (sin (7x))*ctg (7x)