In mathematics, a cube root of a number x is a number a such that a³ = x. All real numbers (except zero) have exactly one real cube root and a pair of complex conjugate cube roots, and all nonzero complex numbers have three distinct complex cube roots. For example, the real cube root of 8, denoted , is 2, because 2³ = 8, while the other cube roots of 8 are -1 + i and -1 - i. The three cube roots of -27i are