Variables are used throughout Algebra, Geometry, and Calculus. They are the basic building blocks. Variables are therefore very important to understand.

A variable is a symbol, such as x, that is used to describe an unknown number. In functions variables often represent not one number, but many different numbers. Understanding variables is essential for you to understanding problems that will need to be graphed.

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What Are Variables?. (2013, March 2). In ClassBrain Math Tutorials. Retrieved 09:29, September 22, 2017, from http://www.classbrainmath.com/introduction-to-equations-defining-variables/
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Cynthia Kirkeby, “What Are Variables?.” ClassBrain Math Tutorials. 2 March 2013, 10:46 UTC. . 22 Sep 2017 <http://www.classbrainmath.com/introduction-to-equations-defining-variables/>.
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Cynthia Kirkeby, 'What Are Variables?', ClassBrain Math Tutorials, 2 March 2013, 10:46 UTC, <http://www.classbrainmath.com/introduction-to-equations-defining-variables/> [accessed 22 September 2017]
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Cynthia Kirkeby, “What Are Variables?.” ClassBrain Math Tutorials, http://www.classbrainmath.com/introduction-to-equations-defining-variables/ [accessed September 22, 2017].
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Cynthia Kirkeby, What Are Variables? [Internet]. ClassBrain Math Tutorials; 2013 March 2, 10:46 UTC [cited 2017 Sep 22]. Available from: http://www.classbrainmath.com/introduction-to-equations-defining-variables/.
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What Are Variables?, http://www.classbrainmath.com/introduction-to-equations-defining-variables/ (last visited Sep. 22, 2017).
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Cynthia Kirkeby, What Are Variables?. ClassBrain Math Tutorials. March 2, 2013, 10:46 UTC. Available at: http://www.classbrainmath.com/introduction-to-equations-defining-variables/. Accessed September 22, 2017.