
Bradford T. answered 02/07/22
Retired Engineer / Upper level math instructor
This is a chain rule exercise.
Might help to rewrite to make the power rule more evident.
y = sin(x1/3) + (sin(7x))1/3
y' = cos(x1/3) (1/3)x-2/3 + (1/3)(sin(7x))-2/3(cos(7x))7
= cos(3√x)/(3 3√(x2))+7cos(7x)/(3 3√sin2(7x))