平方根是幂运算的逆运算。例如： 16 = 4 , 4 2 = 16 , 16 = 16 1 / 2 {\displaystyle {\sqrt {16}}\ =4,4^{2}=16,{\sqrt {16}}\ =16^{1/2}} ，其中 4 2 = 4 {\displaystyle {\sqrt {4^{2}}}\ =4} 。因此，一般来说： x = x 1 / 2 , x n n = x {\displaystyle {\sqrt {x}}\ =x^{1/2},{\sqrt[{n}]{x^{n}}}=x}
![{\displaystyle {\sqrt {x}}\ =x^{1/2},{\sqrt[{n}]{x^{n}}}=x}](https://wikimedia.org/api/rest_v1/media/math/render/svg/415beed10b6ca67c99963c1be2ffd08356af76ae)