## Quick Reference

A square root of a real number *a* is a number *x* such that *x*^{2}=*a*. If *a* is negative, there is no such real number. If *a* is positive, there are two such numbers, one positive and one negative. For *a*≥0, the notation √*a* is used to denote quite specifically the non-negative square root of *a*.

*Subjects:*
Mathematics.

## Related content in Oxford Index

##### Reference entries

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.