Solving Laplace of Plane Wave with x,y,z Coordinates: Troubleshooting Guide

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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!


http://img213.imageshack.us/img213/9532/85490316.jpg


http://img528.imageshack.us/img528/6835/f41cab97f649df5431127b5.png
 
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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!
 
What's k \cdot r when written in terms of cartesian coordinates?
 
Yes.
 
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