*See radical for other uses of the term*

In mathematics, the

*n*-th

**root**or

**radical**of the non-negative real number

*a*, written as , is the unique non-negative real number

*b*such that

*b*

^{n}=

*a*. See square root for the case where

*n*=2.

Operations with radicals are given by the following formulas:

*a*and

*b*are positive.

To every non-zero complex number *a* there are *n* different complex numbers *b* such that *b*^{n} = *a*, so the symbol cannot be used unambiguously. The *n*-th roots of unity are of particular importance.