We can use Green's theorem to understand why the Exact Differential Equation satisfy the conditions it should have ...
How about a DE for more than two variables ?
Eg.dF=P(x,y,z,w)dx+Q(x,y,z,w)dy+R(x,y,z,w)dz+S(x,y,z,w)dw
IF the equation above is an Exact Differential Equation , what...