Let D be a region in .
Let's denote: .
1. Prove that there is no non-trivial first order PDE
such as its set of soloution in D includes all the functions in K.
2. Find two non trivial differential equations of second order which are not equivalent and that all of the functions in K are soloutions for them both.
I'm pretty sure that in 1 we need to get some kind of a contradiction from fact that a function in K can be represented as:
Help is needed