[tex]\sqrt{2\frac{14}{25}} = \sqrt{\frac{2\cdot25+14}{25}} = \sqrt{\frac{64}{25}} = \frac{\sqrt{64}}{\sqrt{25}}=\frac{8}{5} = 1\frac{3}{5}[/tex]
[tex]6,25:7\frac{1}{7} = \frac{625}{100}:\frac{50}{7}=\frac{25}{4}\cdot\frac{7}{50} = \frac{7}{4\cdot2} = \frac{7}{8}[/tex]
[tex]\frac{1}{2}\cdot(-1,4) = \frac{1}{2}\cdot(-\frac{14}{10}) = \frac{1}{2}\cdot(-\frac{7}{5}) = -\frac{7}{10} = -0,7[/tex]
[tex]7,5 - 2\frac{2}{3} = \frac{75}{10}-\frac{8}{3} = \frac{15}{2}-\frac{8}{3} = \frac{45}{6}-\frac{16}{6} = \frac{29}{6} = 4\frac{5}{6}[/tex]
