Posted by haifeng on 2021-03-25 15:55:13 last update 2021-03-25 15:57:53 | Answers (1) | 收藏
求不定积分
\[ \int\frac{\mathrm{d}x}{x^2\sqrt{1+x^2}} \]
[Hint] 令 $x=\frac{1}{t}$ 或 $x=\tan t$
