Can anyone help me with this question? I tried taking the derivative of u with respect to x and then summed the third derivative, but I'm getting nowhere. Any help would be great, thanks. Let u(x1, x2, … , xn) = http://img480.imageshack.us/img480/1694/image0027hm.gif [Broken],[/URL] where a is a constant, and n is given. Find all the values of the constant a, if any, for which the function u satisfies the partial differential equation http://img480.imageshack.us/img480/2918/image0044jl.gif [Broken] .