P(x, ])dr+O(x, y)dy=0.g_og ay ax 通解为: u(x, y)=P(x, yo)dx+.o(x, y)dy C xo Kx Q y P P x y dx Q x y dy   =   ( , ) + ( , ) = 0,且 通解为: ( , ) ( , ) ( , ) . 0 0 u x y P x y0 dx Q x y dy C y y x x =  +  =