对于根式处理，Maple有专门的函数radnormal和rationalize。Mathematica中对于简单的可以用Simplify/FullSimplify，复杂点就不行了，例如：
Sqrt[10 - 6 Sqrt[2] + 5 Sqrt[3] - 4 Sqrt[6]]，
一种方法是用待定系数法，
10 - 6 Sqrt[2] + 5 Sqrt[3] - 4 Sqrt[6] == (a Sqrt[2] + b Sqrt[3] + c Sqrt[6] + d)^2
10 - 6 Sqrt[2] + 5 Sqrt[3] - 4 Sqrt[6] == 2 a^2 + 3 b^2 + 6 c^2 + d^2 + Sqrt[2] (6 b c + 2 a d) + Sqrt[3] (4 a c + 2 b d) + Sqrt[6] (2 a b + 2 c d)
Solve[{10 == 2 a^2 + 3 b^2 + 6 c^2 + d^2, -6 == 6 b c + 2 a d, 5 == 4 a c + 2 b d, -4 == 2 a b + 2 c d}, {a, b, c, d}, Rationals]
觉得可以用SolveAlways做，但是没搞出来，
Sqrt[10 - 6 Sqrt[2] + 5 Sqrt[3] - 4 Sqrt[6]]，
一种方法是用待定系数法，
10 - 6 Sqrt[2] + 5 Sqrt[3] - 4 Sqrt[6] == (a Sqrt[2] + b Sqrt[3] + c Sqrt[6] + d)^2
10 - 6 Sqrt[2] + 5 Sqrt[3] - 4 Sqrt[6] == 2 a^2 + 3 b^2 + 6 c^2 + d^2 + Sqrt[2] (6 b c + 2 a d) + Sqrt[3] (4 a c + 2 b d) + Sqrt[6] (2 a b + 2 c d)
Solve[{10 == 2 a^2 + 3 b^2 + 6 c^2 + d^2, -6 == 6 b c + 2 a d, 5 == 4 a c + 2 b d, -4 == 2 a b + 2 c d}, {a, b, c, d}, Rationals]
觉得可以用SolveAlways做，但是没搞出来，
