от Xixibg » 21 Окт 2011, 14:16
[tex]1.\frac{\sqrt{14}\sqrt{2}+7}{\sqrt{7}}=\frac{\sqrt{7}(\sqrt{7}\sqrt{2}\sqrt{2}+7)}{\sqrt{7}\sqrt{7}}=\frac{2.7+7\sqrt{7}}{7}=2+\sqrt{7}[/tex]
[tex]2.x=\frac{\sqrt{8}}{2}=\frac{2\sqrt{2}}{2}=\sqrt{2}[/tex]
[tex]A=(x-\sqrt{3})(x+\sqrt{3})=x^2-(\sqrt{3})^2=x^2-3=(\sqrt{2})^2-3=2-3=-1[/tex]
[tex]3.\frac{3\sqrt{2}+\sqrt{6}}{2\sqrt{3}}=\frac{3\sqrt{2}+\sqrt{3}\sqrt{2}}{2\sqrt{3}}=\frac{\sqrt{2}(3+\sqrt{3})\sqrt{3}}{2\sqrt{3}\sqrt{3}}=\frac{3\sqrt{2}(1+\sqrt{3})}{6}=\frac{\sqrt{2}(1+\sqrt{3})}{2}=\frac{\sqrt{2}+\sqrt{6}}{2}[/tex]
[tex]4.\frac{2}{\sqrt{3}}+\frac{\sqrt{3}}{\sqrt{3}+2}=\frac{2\sqrt{3}}{\sqrt{3}\sqrt{3}}+\frac{\sqrt{3}(2-\sqrt{3})}{(\sqrt{3}+2)(2-\sqrt{3})}=\frac{2\sqrt{3}}{3}+\frac{3\sqrt{3}(2-\sqrt{3})}{3}=\frac{8\sqrt{3}-9}{3}[/tex]
[tex]5.|4-3\sqrt{2}|+|4\sqrt{3}-7|+\frac{10\sqrt{3}}{4+\sqrt{6}}=-4+3\sqrt{2}-4\sqrt{3}+7+\frac{(4-\sqrt{6})10\sqrt{3})}{(4+\sqrt{6})(4-\sqrt{6})}=3+3\sqrt{2}-4\sqrt{3}+\frac{(4-\sqrt{6})10\sqrt{3}}{10}[/tex]
[tex]=3+3\sqrt{2}-4\sqrt{3}+4\sqrt{3}-3\sqrt{2}=3[/tex]