Đáp án đúng: A \[E=\dfrac{\sqrt{5+2\sqrt{6}}}{\sqrt{2}+\sqrt{3}}\\=\dfrac{\sqrt{3+2\sqrt{3.2}+2}}{\sqrt{2}+\sqrt{3}}\\=\dfrac{\sqrt{{{\left( \sqrt{3}+\sqrt{2} \right)}^{2}}}}{\sqrt{2}+\sqrt{3}}\\=\dfrac{\left| \sqrt{3}+\sqrt{2} \right|}{\sqrt{2}+\sqrt{3}}=1\]
