Tính B:
2B = \sqrt{\sqrt{961} + 8\sqrt{10} + 4\sqrt{15} + 4\sqrt{6}}
2B = \sqrt{31 + 2\sqrt{8}.\sqrt{20} + 2\sqrt{3}\sqrt{20} + 2\sqrt{8}.\sqrt{3}}
2B = \sqrt{20 + 8 + 3 + 2\sqrt{8}.\sqrt{20} + 2\sqrt{3}\sqrt{20} + 2\sqrt{8}.\sqrt{3}}
2B = \sqrt{(\sqrt{8} + \sqrt{20} + \sqrt{3})^2} =...