if the fourth power of a number x is equal to a, that is, the continuous multiplication of four x is equal to a, then the number x is called the fourth root of a.

any number has four and only four fourth roots. properties of fourth roots: (1) any number that is not 0 has four fourth roots. ⑵the fourth root of 0 is 0. generally, if the fourth root of a number x is equal to a, then the number x is called the fourth root of a. that is, if x⁴=a, then x is called the cube root of a. 0 is the fourth root of 0.