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

• а) $$ \frac{4}{5} - \frac{3}{4} = \frac{4 \cdot 4}{5 \cdot 4} - \frac{3 \cdot 5}{4 \cdot 5} = \frac{16}{20} - \frac{15}{20} = \frac{16-15}{20} = \frac{1}{20} $$
• в) $$ \frac{2}{3} - \frac{1}{7} = \frac{2 \cdot 7}{3 \cdot 7} - \frac{1 \cdot 3}{7 \cdot 3} = \frac{14}{21} - \frac{3}{21} = \frac{14-3}{21} = \frac{11}{21} $$
• д) $$ \frac{5}{6} - \frac{5}{12} = \frac{5 \cdot 2}{6 \cdot 2} - \frac{5}{12} = \frac{10}{12} - \frac{5}{12} = \frac{10-5}{12} = \frac{5}{12} $$
• б) $$ \frac{3}{10} - \frac{2}{7} = \frac{3 \cdot 7}{10 \cdot 7} - \frac{2 \cdot 10}{7 \cdot 10} = \frac{21}{70} - \frac{20}{70} = \frac{21-20}{70} = \frac{1}{70} $$
• г) $$ \frac{5}{9} - \frac{1}{3} = \frac{5}{9} - \frac{1 \cdot 3}{3 \cdot 3} = \frac{5}{9} - \frac{3}{9} = \frac{5-3}{9} = \frac{2}{9} $$
• е) $$ \frac{2}{13} - 0 = \frac{2}{13} $$

Ответ: а) 1/20; в) 11/21; д) 5/12; б) 1/70; г) 2/9; е) 2/13.