https://zhdel.miraheze.org/wiki/%E8%8B%B9%E6%9E%9C%E5%85%AC%E5%8F%B8%E4%BD%BF%E7%94%A8%E8%BF%87%E7%9A%84%E6%AD%8C%E6%9B%B2%E5%88%97%E8%A1%A8
x^(1/n)，(1/2)平方根，(1/3)立方根，(1/n)n次方根
