Origins of Two Familiar Math Terms

Al-Khwarizmi's other book, The Compendious Book on Calculation by Completion and Balancing, contained a method known as al-jabr. This is the method of removing negative amounts from an equation by adding that amount to each side. That is, for ${\displaystyle x^{2}=x-2x^{2}}$ one would apply al-jabr by adding ${\displaystyle 2x^{2}}$ to both sides to get ${\displaystyle 3x^{2}=x}$. The term algebra is derived from the word al-jabr.