P(x)dx 中y y=c(x) M(x)N(y) dh M 9()= +p(x)y=e(r) dx N d Pdx+ody=0 X=x+ Y=y+k Oy Ox P(x)d u=e +1N Z=y ax+by+c y'+P(x)y=o(x)y f( dx a,x+b,y+CI (1-n)P(x)ax Q y P Pdx Qdy   =   + = 0 M(x)N( y) dx dy = ( ) 1 N y  = N M x y dx dy = ( ) = − x y u = xM + yN = 1  ( ) 1 1 1 a x b y c ax by c f dx dy + + + + = Y y k X x h = + = + P(x) y Q(x) dx dy + =  = − P x dx y c x e ( ) ( )  = P x dx e ( )  n y + P(x) y = Q(x) y n z y − = 1  = −n P x dx n e y 1 (1 ) ( ) 