Write an iterated triple integral in the order $dz\,dy\,dx$ for the volume of the region bounded below by the $xy$-plane and above by the paraboloid $z = x^2 + y^2$ and lying inside the cylinder $x^2 + y^2 = 4$?
From the question, I know that $z=0$, but how can I write it as a triple integral $dz\,dy\,dx$?
$$\iiint dz\,dy\,dx$$