Expressions and Equations
Variables Review of Terminology An expression is a "phrase" that represents a number. An equation sets two expressions equal to each other. A variable is a symbol used to represent a number. In the expression?8x?+ 17?,?x?is the variable. In the equation??= 25?,?y?is the variable. Variables need not be letters; for example, the expression?6?+ 2?contains the variable?. An expression or equation may contain more than one variable. The expression?7 - 3r?+ 12t?contains the variables?r?and?t?, and the equation?6y?= 24x?contains the variables?x?and?y?. An algebraic expression is an expression that contains one or more variables. An algebraic equation is an equation that contains one or more variables.