Toán căn là phép toán nghịch đảo của phép toán lủy thừa .
Với
Căn 2
0 = E r r o r {\displaystyle {\sqrt {0}}=Error} 1 = 1 {\displaystyle {\sqrt {1}}=1} − 1 = j {\displaystyle {\sqrt {-1}}=j}
a n m = a m n = a 1 m n {\displaystyle {\sqrt[{m}]{\sqrt[{n}]{a}}}={\sqrt[{mn}]{a}}=a^{\frac {1}{mn}}}
a b = a b {\displaystyle {\sqrt {\frac {a}{b}}}={\frac {\sqrt {a}}{\sqrt {b}}}} a b n = a n b n {\displaystyle {\sqrt[{n}]{\frac {a}{b}}}={\frac {\sqrt[{n}]{a}}{\sqrt[{n}]{b}}}}
a b {\displaystyle {\sqrt {ab}}} = a {\displaystyle {\sqrt {a}}} b {\displaystyle {\sqrt {b}}}
a a = a 2 × a = a 3 {\displaystyle a{\sqrt {a}}={\sqrt {a^{2}\times a}}={\sqrt {a^{3}}}}
a n = a a n − 2 {\displaystyle {\sqrt {a^{n}}}=a{\sqrt {a^{n-2}}}}
![{\displaystyle {\sqrt[{m}]{\sqrt[{n}]{a}}}={\sqrt[{mn}]{a}}=a^{\frac {1}{mn}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/83064172516d2185efbd65172ed7cc9d3e701284)
![{\displaystyle {\sqrt[{n}]{\frac {a}{b}}}={\frac {\sqrt[{n}]{a}}{\sqrt[{n}]{b}}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/372ddb7d13541806e35a6053ba614df98a87b655)
