Question

Нужно избавиться от иррационала., .

Answer 1

$\dfrac{1}{\sqrt{2}+\sqrt{5}-\sqrt{3}}=\dfrac{(\sqrt{2}+\sqrt{5})+\sqrt{3}}{((\sqrt{2}+\sqrt{5})-\sqrt{3})((\sqrt{2}+\sqrt{5})+\sqrt{3})}=\\\\=\dfrac{\sqrt{2}+\sqrt{5}+\sqrt{3}}{(\sqrt{2}+\sqrt{5})^2-(\sqrt{3})^2}=\dfrac{\sqrt{2}+\sqrt{5}+\sqrt{3}}{2+2\sqrt{10}+5-3}=\dfrac{\sqrt{2}+\sqrt{5}+\sqrt{3}}{4+2\sqrt{10}}=\\\\=\dfrac{\sqrt{2}+\sqrt{5}+\sqrt{3}}{2(2+\sqrt{10})}=\dfrac{(\sqrt{2}+\sqrt{5}+\sqrt{3})(2-\sqrt{10})}{2(2+\sqrt{10})(2-\sqrt{10})}=$

$=\dfrac{2\sqrt{2}-\sqrt{20}+2\sqrt{5}-\sqrt{50}+2\sqrt{3}-\sqrt{30}}{2(2^2-(\sqrt{10})^2)}=\\\\=\dfrac{2\sqrt{2}-2\sqrt{5}+2\sqrt{5}-5\sqrt{2}+2\sqrt{3}-\sqrt{30}}{2(4-10)}=\\\\=\dfrac{-3\sqrt{2}+2\sqrt{3}-\sqrt{30}}{-12}=\dfrac{3\sqrt{2}-2\sqrt{3}+\sqrt{30}}{12}$