Pronunciation: /ˈræʃ.nl/ Explain

A mathematical object is rational if it can be expressed as a ratio.

  1. A rational number is a number that can be expressed as the ratio of two integers.
  2. A rational expression is an expression that contains a ratio of two polynomials.
  3. A rational function is a function that contains a rational expression. A rational function is also called a fractional equation.
  4. A rational root is a root of a polynomial that is a rational number.


  1. McAdams, David E.. All Math Words Dictionary, rational. 2nd Classroom edition 20150108-4799968. pg 150. Life is a Story Problem LLC. January 8, 2015. Buy the book

Cite this article as:

McAdams, David E. Rational. 3/28/2019. All Math Words Encyclopedia. Life is a Story Problem LLC. https://www.allmathwords.org/en/r/rational.html.

Revision History

12/21/2018: Reviewed and corrected IPA pronunication. (McAdams, David E.)
12/5/2018: Removed broken links, updated license, implemented new markup. (McAdams, David E.)
2/10/2009: Added definition of rational equation. (McAdams, David E.)
2/6/2009: Added rational root to list. (McAdams, David E.)
1/19/2009: Initial version. (McAdams, David E.)

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