от alexander_ivanov » 24 Окт 2011, 11:56
1.
[tex]\frac{10}{1+\sqrt{5}+\sqrt{6}}.\frac{1-(\sqrt{5}+\sqrt{6})}{1-(\sqrt{5}+\sqrt{6})}=\frac{10(1-\sqrt{5}-\sqrt{6})}{1-11-2\sqrt{30}}=\frac{\cancel{2}.5(1-\sqrt{5}-\sqrt{6})}{\cancel{2}(5-sqrt{30})}.\frac{5+\sqrt{30}}{5+\sqrt{30}}[/tex]
[tex]=-\frac{\cancel{5}(1-\sqrt{5}-\sqrt{6})(5+\sqrt{30})}{\cancel{5}}=(\sqrt{5}+sqrt{6}-1)(5+\sqrt{30})=5\sqrt{5}+5\sqrt{6}-5+5\sqrt{6}+6\sqrt{5}-\sqrt{30}=11\sqrt{5}+10\sqrt{6}-5-[/tex]
[tex]-\sqrt{30}[/tex] сори някъде съм имал грешка при смятането , това е решението
2.[tex]\underbrace{\frac{2}{\sqrt{3}} +\frac{2}{3\sqrt{3}}}_{3\sqrt{3}}-(\underbrace{\frac{3}{4\sqrt{3}}+ \frac{\sqrt{3}}{6}}_{12\sqrt{3}})=\underbrace{\frac{8}{3\sqrt{3}}-\frac{9+6}{12\sqrt{3}}}_{12\sqrt{3}}=\frac{32-15}{12\sqrt{3}}.\frac{\sqrt{3}}{\sqrt{3}}=\frac{17\sqrt{3}}{36}[/tex]