1. The problem statement, all variables and given/known data I have D(p(x)) = (the second derivative of p with respect to x ) - (2 derivative of p with respect to x) + p Proof that D(p(x)) is not an isomorphism 2. Relevant equations 3. The attempt at a solution Just by watching the problem it seems I can assign one unique value to D(p(x)) and receive an unique image. It seems by inspection that it is one to one. It also seems onto by inspection.