==amp;amp;gt;y(1-x²)dy-xy²dx+cosxsinxdx=0

==amp;amp;gt;(1-x²)d(y²)-y²d(x²)+sin(2x)dx=0

==amp;amp;gt;2(1-x²)d(y²)+2y²d(1-x²)+sin(2x)d(2x)=0

==amp;a（本章未完，请翻页）

www.。m.