i am having hard time sketching the domain of this :
$$ \ \int_0^1\int_0^{1-x^2}\int_0^y f(x,y,z){dz}{dy}{dx} $$
is there an easy way to do that ? i got like cylinder and planes and its hard to see the Volume domain
The question asking to sketch this " simple " domain

You integrate with respect to $z$ first, keeping $x,y$ fixed. For any $(x,y), z$ ranges from $0\to y$. That means you're integrating below the plane $y=z$. Next you integrate with respect to $y$, keeping $x$ fixed. $y$ ranges from $0\to1-x^2$. This means you are integrating over the region below the parabola $y=1-x^2$, from $x=0\to1$, where it intersects the $x$ axis.