Chắc đề là: \(\dfrac{\sqrt{2}}{\sqrt{5}+1}-\sqrt{\dfrac{2}{3-\sqrt{5}}}\)
\(=\dfrac{\sqrt{2}\left(\sqrt{5}-1\right)}{\left(\sqrt{5}+1\right)\left(\sqrt{5}-1\right)}-\sqrt{\dfrac{2\left(3+\sqrt{5}\right)}{\left(3+\sqrt{5}\right)\left(3-\sqrt{5}\right)}}=\dfrac{\sqrt{2}\left(\sqrt{5}-1\right)}{4}-\sqrt{\dfrac{6+2\sqrt{5}}{4}}\)
\(=\dfrac{\sqrt{10}-\sqrt{2}}{4}-\sqrt{\left(\dfrac{\sqrt{5}+1}{2}\right)^2}=\dfrac{\sqrt{10}-\sqrt{2}}{4}-\dfrac{\sqrt{5}+1}{2}=\dfrac{\sqrt{10}-\sqrt{2}-2\sqrt{5}-2}{4}\)
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