Question

Помогите пожалуйста срочноо!! дам 50 баллов​

Answer 1

$\frac{25}{\sqrt7-\sqrt2}=\frac{25(\sqrt7+\sqrt2)}{(\sqrt7-\sqrt2)(\sqrt7+\sqrt2)}=\frac{25(\sqrt7+\sqrt2)}{7-2}=\frac{25(\sqrt7+\sqrt2)}{5}=5(\sqrt7+\sqrt2)\\\\\frac{85}{2\sqrt5-1}=\frac{85(2\sqrt5+1)}{(2\sqrt5-1)(2\sqrt5+1)}=\frac{85(2\sqrt5+1)}{20-1}=\frac{85(2\sqrt5+1)}{19}\\\\\frac{1}{1-\sqrt2}=\frac{1+\sqrt2}{(1-\sqrt2)(1+\sqrt2)}=\frac{1+\sqrt2}{1-2}=\frac{1+\sqrt2}{-1}=-1-\sqrt 2$

$\\\\\frac{26}{\sqrt5-2}=\frac{26(\sqrt5+2)}{(\sqrt5-2)(\sqrt5+2)}=\frac{26(\sqrt5+2)}{5-4}=\frac{26(\sqrt5+2)}{1}=26(\sqrt5+2)\\\\\frac{12}{3+\sqrt5}=\frac{12(3-\sqrt5)}{(3+\sqrt5)(3-\sqrt5)}=\frac{12(3-\sqrt5)}{9-5}=\frac{12(3-\sqrt5)}{4}=3(3-\sqrt5)$