b) \(B=\left(2+\sqrt{7}\right)\sqrt{11-4\sqrt{7}}-\dfrac{\sqrt{20}+5}{\sqrt{5}+2}\)
\(B=\left(2+\sqrt{7}\right)\sqrt{2^2-2\cdot2\cdot\sqrt{7}+\left(\sqrt{7}\right)^2}-\dfrac{\sqrt{5}\left(\sqrt{5}+2\right)}{\sqrt{5}+2}\)
\(B=\left(2+\sqrt{7}\right)\sqrt{\left(2-\sqrt{7}\right)^2}-\sqrt{5}\)
\(B=\left(2+\sqrt{7}\right)\left|2-\sqrt{7}\right|-\sqrt{5}\)
\(B=-\left(2+\sqrt{7}\right)\left(2-\sqrt{7}\right)-\sqrt{5}\)
\(B=-\left(4-7\right)-\sqrt{5}\)
\(B=3-\sqrt{5}\)
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