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square root
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The French mathematician René Descartes (1596–1650) demonstrated that the square root of any line segment could be constructed by the simple, but ingenious, addition of a line segment with unit length.
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square root

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On the Web:
OpenStax - Elementary Algebra 2e - Simplify and Use Square Roots (June 05, 2025)

square root, in mathematics, a factor of a number that, when multiplied by itself, gives the original number. For example, both 3 and –3 are square roots of 9. As early as the 2nd millennium bc, the Babylonians possessed effective methods for approximating square roots. See root.

This article was most recently revised and updated by William L. Hosch.