Concept

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 \Leftrightarrow 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 4 x + 100

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