2021-005

Given that \( \sin(xyz) = x + 2z + y \), find the correct answer for the partial derivative of \( z \) with respect to \( y \), that is \( \partial z / \partial y \).

1. \( [1 - yz\cos(xyz)] / [xy\cos(xyz) - 2] \)
2. \( [1 + yz\cos(xyz)] / [xy\cos(xyz) - 2] \)
3. \( [1 + xz\cos(xyz)] / [xy\cos(xyz) - 2] \)
4. \( [1 - xz\cos(xyz)] / [xy\cos(xyz) - 2] \)
5. none of the above

Original idea by: Soroor Salavati