- #1
yungman
- 5,718
- 240
This is part of a bigger derivation of Green's function. The book just jump to the ending and I cannot understand how to do this. I need someone to give me guidence how to proof this:
[tex] \frac{x}{r} \frac{\partial u}{\partial x} + \frac{y}{r} \frac{\partial u}{\partial y} +\frac{z}{r} \frac{\partial u}{\partial z} \;=\; \frac{\partial u}{\partial r} [/tex]
Where
[tex] r=\sqrt{x^2+y^2+z^2}[/tex]
This is not a homework problem.
Thanks
[tex] \frac{x}{r} \frac{\partial u}{\partial x} + \frac{y}{r} \frac{\partial u}{\partial y} +\frac{z}{r} \frac{\partial u}{\partial z} \;=\; \frac{\partial u}{\partial r} [/tex]
Where
[tex] r=\sqrt{x^2+y^2+z^2}[/tex]
This is not a homework problem.
Thanks