Rút gọn B = √11 - 2√10

$Rút gọn$

:
$$\begin{gathered} B=\sqrt{11-2\sqrt{10}} \\ C=\sqrt{4-\sqrt{7}}-\sqrt{4+\sqrt{7}} \\ D=(\sqrt{22}+7\sqrt{2})\sqrt{30-7\sqrt{11}} \end{gathered}$$