## Laplace of plane wave

This is what I got for Nabla and Laplace of plane wave. I have problems when I try to write out it with x, y, z coordinates. Can somebody help me? Thanks!

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 What problems do you have? You should get the same thing, just written in terms of the components of $k$ and $r$.
 @Muphrid I know the result, but I have problems with procedure. Can you write down this equation; or just the start? Thanks!

## Laplace of plane wave

What's $k \cdot r$ when written in terms of cartesian coordinates?

 Yes.

 Tags laplace, nabla, plane wave