Problem 1232 (difficulty: 2/10)

"Let \(\displaystyle f(x,y)=\hbox{log}\sqrt{(x-a)^2+(y-b)^2}\). Show that \(\displaystyle {\partial ^2 f\over \partial x^2}+{\partial^2f \over \partial y^2}=0\).

Give me another random problem!