Why Do We Use The Letter 'X' To Represent The Unknown?

Have you ever wondered why we use the letter 'x' to represent the unknown?

When thinking of the unknown 'x' you might think of algebra or other types of mathematics equations at first, but we can also find it elsewhere, such as The X-Files, Project-X and X-Prize to name a few.

Terry Moore was curious about the origin of 'x' as the unknown, so he did the research and found out so we don't have to.

In this short and humorous TedTalk, he gives us the surprising answer.