62 views

If $z= xy \text{ ln} (xy)$, then

1. $x\frac{\partial z}{\partial x}+y\frac{\partial z}{\partial y}= 0 \\$
2. $y\frac{\partial z}{\partial x}= x\frac{\partial z}{\partial y} \\$
3. $x\frac{\partial z}{\partial x}= y\frac{\partial z}{\partial y} \\$
4. $y\frac{\partial z}{\partial x}+x\frac{\partial z}{\partial y}= 0$