Uh oh! Wolfram|Alpha doesn't run without JavaScript.
Please enable JavaScript. If you don't know how, you can find instructions
here
.
Once you've done that, refresh this page to start using Wolfram|Alpha.
自己安慰自己的视频教程|网址:qy81.com_2790a.htm
Natural Language
Math Input
Extended Keyboard
Examples
Upload
Random
