I am asked to evaluate the following integral: $$\int\int \text{curl} \ \vec{F} \cdot d\vec{S}$$ where $F = (y,-x,zx^3y^2)$ and $S$ is the surface given by $x^2 + y^2 + 3z^2 = 1$ with $z \leq 0$.
I did not have any problem with any other exercises of this kind. But this one is hard.
Any hint would be appreciated.