Question

show that z=e^x cos y satisfies the Laplace equation

Answer 1

so u must show that\[z_{xx}+z_{yy}=0\]if im not wrong

Answer 2

div(grad z)=0 is what we want, eh?
ah @mukushla beat me as usual

Answer 3

just find 2º derivatives and add the results to check if it matches this equation