## Basic College Mathematics (9th Edition)

A variable is a letter that represents a number. Examples:: $x, y, \text{ and } z$ An expression is a sum, difference, product, or quotient of numbers and variables/letters. Examples: $2x, 5x-3y, \text{ and } \frac{9x}{5}+2$ An equation is a mathematical statements that says two expressions are equal to each other. Examples: $2x=4 \\3x-5y=8 \\x^2-16=0$
A variable is a letter that represents a number. Examples of variables are: $x, y, \text{ and } z$ An expression is a sum, difference, product, or quotient of numbers and variables/letters. Examples are: $2x, 5x-3y, \text{ and } \frac{9x}{5}+2$ An equation is a mathematical statements that says two expressions are equal to each other. Examples are: $2x=4 \\3x-5y=8 \\x^2-16=0$