Проверочная работа №3. 1. Найдите разность: а) \frac{4}{5} - \frac{3}{4}; б) \frac{3}{10} - \frac{2}{7}; г) \frac{5}{9} - \frac{1}{7}; д) \frac{5}{6} - \frac{5}{12}; е) \frac{2}{13} - 0.

а) \frac{4}{5} - \frac{3}{4} = \frac{4*4}{5*4} - \frac{3*5}{4*5} = \frac{16}{20} - \frac{15}{20} = \frac{1}{20}. б) \frac{3}{10} - \frac{2}{7} = \frac{3*7}{10*7} - \frac{2*10}{7*10} = \frac{21}{70} - \frac{20}{70} = \frac{1}{70}. г) \frac{5}{9} - \frac{1}{7} = \frac{5*7}{9*7} - \frac{1*9}{7*9} = \frac{35}{63} - \frac{9}{63} = \frac{26}{63}. д) \frac{5}{6} - \frac{5}{12} = \frac{5*2}{6*2} - \frac{5}{12} = \frac{10}{12} - \frac{5}{12} = \frac{5}{12}. е) \frac{2}{13} - 0 = \frac{2}{13}.