The subject of algebra was invented around the 9th century by which people?

The foundations of what we know as algebra today were established during the Islamic Golden Age. At the heart of this development was the Persian mathematician Muhammad ibn Musa al-Khwarizmi, who lived and worked in 9th-century Baghdad. He was a scholar at the renowned House of Wisdom, an intellectual center where knowledge from various cultures was translated, studied, and synthesized. It was here that al-Khwarizmi wrote a groundbreaking book around 825 CE, which introduced a systematic approach to solving linear and quadratic equations.

His treatise, "The Compendious Book on Calculation by Completion and Balancing," provided a new way of thinking about mathematical problems. The very word "algebra" is derived from "al-jabr," an Arabic term from his book's title that refers to the process of "restoration" or "completion," such as moving a negative term to the other side of an equation. This work was revolutionary because it presented a general method for solving a whole class of problems, rather than just offering solutions to specific, individual ones.

Al-Khwarizmi's goal was practical, aiming to solve real-world issues involving inheritance, trade, and land measurement. His work not only established algebra as an independent mathematical discipline but also introduced Hindu-Arabic numerals to the Western world. This system, which included the concept of zero, was far more efficient for calculation than the Roman numerals used in Europe at the time. For these foundational contributions, al-Khwarizmi is often called the "father of algebra."