# Terry Moore: Why is 'x' the unknown?

Why is 'x' the symbol for an unknown? In this short and funny talk, Terry Moore gives the surprising answer.

- Kind: Talk
- Year: 2012
- Runtime: 3 min
- By: TED.com
- Genres: Education, History
- Archive: [Internet Archive](https://archive.org/details/TerryMoore_2012)
- Licence or status: [CC BY-NC-ND 3.0](http://creativecommons.org/licenses/by-nc-nd/3.0/) (as the archive states it)
- Who can watch: Tweens profiles and older (the archive gives no rating; placed by Invisible Network from its collection and subjects)

[Watch now](https://invisiblenetwork.ai/watch/archive/ia/TerryMoore_2012?play=1)