The simplest and fastest method of solving Exact Differential Equation   by developing the idea of Basic Functions
  This paper concerns exact differential equations. First, I define two types of functions which I have named Basic Function of Type One and Basic Function of Type Two. I then derive the property and theorems of these functions. Finally, by applying the property and theorems of Basic Functions, I establish the method of solving exact differential equation with n variables which is significantly simpler and faster than the standard method. 
Seyed Ahmad Sabok-Sayr