Question

  câu cc Chi tiêtiêttiết nhất 

Answer 1

\(C=\left(\dfrac{\sqrt{10}+\sqrt{5}}{\sqrt{2}+1}+\dfrac{\sqrt{21}-\sqrt{7}}{1-\sqrt{3}}\right):\dfrac{1}{\sqrt{7}-\sqrt{5}}\)

\(=\left(\dfrac{\sqrt{5}\left(\sqrt{2}+1\right)}{\sqrt{2}+1}+\dfrac{\sqrt{7}\left(\sqrt{3}-1\right)}{-\left(\sqrt{3}-1\right)}\right)\cdot\left(\sqrt{7}-\sqrt{5}\right)\)

\(=\left(\sqrt{5}-\sqrt{7}\right)\left(\sqrt{7}-\sqrt{5}\right)\)

\(=\sqrt{35}-5-7+\sqrt{35}=2\sqrt{35}-12\)