History of Algebra

al Khwarizmi & Islamic Mathematics

In 820 AD, the Persian Mathematician, Muḥammad ibn Mūsā al-Khwārizmī wrote "The Compendious Book on Calculation by Completion and Balancing" (الكتاب المختصر في حساب الجبر والمقابلة al-Kitāb al-mukhtaṣar fī ḥisāb al-jabr wal-muqābala) which coined the word Algebra meaning "The Restoration".

In his book, he used methods like "Completing-the-Square" to solve quadratic equations.

Why is x the unknown?

This is a disputed fact because of multiple possible origins. However, one prevailing theory suggest that it is because of the Arabic word, فالشيء (al-shalan), used in ancient Arabic textbooks which means "The Thing".

Furthermore, the sha sound had no Spanish equivalent in translation resulting in the Greek symbol Chi (X) used instead.