# Algebra

## Algebra (Encyclopedia of Science)

Algebra is often referred to as a generalization of arithmetic: problems and operations are expressed in terms of variables as well as constants. A constant is some number that always has the same value, such as 3 or 14.89. A variable is a number that may have different values. In algebra, letters such as a, b, c, x, y, and z are often used to represent variables. In any given situation, a variable such as x may stand for one, two, or any number of values. For example, in the expression x + 5 = 7, the only value that x can have is 2. In the expression x2 = 4, however, x can be either +2 or . And in the expression x + y = 9, x can have an unlimited number of values, depending on the value of y.

Origins of algebra

Algebra became popular as a way of expressing mathematical ideas in the early ninth century. Arab mathematician Al-Khwarizmi is credited with writing the first algebra book, Al-jabr waŹ¾l Muqabalah, from which the English word algebra is derived. The title of the book translates as "restoring and balancing," which refers to the way in which equations are handled in algebra. Al-Khwarizmi's book was influential in its day and remained the most important text in algebra for many years.

Al-Khwarizmi did not use variables in the same way they are used today. He concentrated instead on developing procedures and rules for...

(The entire section is 962 words.)