Ta có: \(B=\left(\dfrac{4}{\sqrt{3}+1}-\dfrac{1}{2-\sqrt{3}}-\dfrac{6}{3-\sqrt{3}}-\dfrac{1}{\sqrt{5}-2}\right)\cdot\left(9-\sqrt{5}\right)\)
\(=\left(2\sqrt{3}-2-2-\sqrt{3}-3-\sqrt{3}-\sqrt{5}-2\right)\cdot\left(9-\sqrt{5}\right)\)
\(=-\left(9+\sqrt{5}\right)\left(9-\sqrt{5}\right)\)
=-81+5
=-76