Variable

A variable is a symbol used to represent an unknown quantity. Often, variables represent fixed but unknown numbers. Variables are usually denoted with letters such as x. x+1=8 In this case, x is a variable in an equation. Solving this equation for x will identify the value of x that makes the equation true. x+1=8 ⇔ x=7 Alternatively, a variable can be used to represent a quantity that changes. Izabella's income varies depending on the number of hours she works. She receives a fixed salary of$100 per week plus$4 per hour. In this case, Izabella's weekly income could be different every week, depending on the number of hours she works. Therefore, the use of a variable is appropriate. Let x be the hours that Izabella works in a week. Her income can be written by adding the fixed $100 to the $4 per hour. Izabella's Weekly Income 4x+100