Why is the “X” the unknown

“Millions of years passed,

Millions of theorems derived,

Millions of formulas made.

But still “X” is unknown”.

We all learn maths in high school, equation like quadratic, cubic function often use X for the variable that we want to solve for. And many of you may have question why people use “X” to represent the unknown? In mathematics, we often use the letter X to represent the unknown quantity. But now Xis everywhere in our society. People use X to represent something that is explainable or unknown, such as X-ray, X file. But why people love to use X to represent unknown?

Arabic is a highly logical language, every part of a sentence is precise and carry a lot of information. That is one of the reasons why the basis of mathematics, science and engineering were formed by the Persians, the Arabs and the Turks. A lot of texts written in Arabic, contained the mathematical ideas finally arrived to Europe around 11th, 12th century. And Europeans were highly interest in translating the texts into their language. However, there were problems in translating theses texts. One problem is that, Europeans cannot pronounce some of the Arabic words without a lot of practices.

Also, there are some sounds not really able to represent by the characters in European languages. One of the example is that the letter which makes sound “sheen” and it is the first letter of the word shalan which means some unknown, undefined thing. Now we can make it definite by adding the two little I like things at the end alshalan, the unknown things. This word appeared in the early mathematical texts and articles, such as the derivation of proofs.

The translator at that time cannot translate this proof into Spanish because there is no “sh” sound in their language. So they borrowed the “ck” sound from Greek which has letter kai, and it look really like an X. Later on, these translated materials translate once again into common European language-Latin. Translating simply replaces the Greek letter kai with X. And this texts form the basis of mathematics for almost 600 years. And now, people get used to using the letter X to represent the unknown.

“I heard you are good in algebra,

can you substitute my X without asking Y?”.

M.Nasreen