Posted by haifeng on 2017-04-21 20:26:48 last update 2017-04-21 20:26:48 | Answers (1) | 收藏
\[ \frac{dy}{dx}-\frac{2y}{x}=-x^2 y^2. \]
[Hint] 注意 $(\frac{1}{y})'=-\frac{1}{y^2}y'$.
