Rút gọn a) A = $\sqrt{\sqrt{6} + \sqrt{3 + 2\sqrt{2}}}$ - $\sqrt{3 + 2\sqrt{2}}$ $\times$ $\sqrt{\sqrt{6} - \sqrt{3 + 2\sqrt{2}}}$
b) B = $\sqrt{8 + 2\sqrt{15}}$ + $\sqrt{12 - \sqrt{140}}$
c) C = $\sqrt{3 + \sqrt{5}}$ + $\sqrt{7 - 3\sqrt{5}}$ - $\sqrt{2}$
d) D = $\sqrt{\sqrt{3} - \sqrt{\sqrt{2} + \sqrt{12} + \sqrt{18 - \sqrt{128}}}}$