Решение примеров Риши

Ниже представлены решения примеров из карточки. Для удобства записи в тетрадь приведены основные этапы приведения дробей к общему знаменателю. Левый столбец: 1) \(\frac{1}{20} + \frac{1}{15} = \frac{3}{60} + \frac{4}{60} = \frac{7}{60}\) 2) \(\frac{2}{9} + \frac{4}{15} = \frac{10}{45} + \frac{12}{45} = \frac{22}{45}\) 3) \(\frac{5}{12} + \frac{4}{9} = \frac{15}{36} + \frac{16}{36} = \frac{31}{36}\) 4) \(\frac{7}{8} - \frac{3}{20} = \frac{35}{40} - \frac{6}{40} = \frac{29}{40}\) 5) \(\frac{1}{12} + \frac{1}{18} = \frac{3}{36} + \frac{2}{36} = \frac{5}{36}\) 6) \(\frac{2}{25} + \frac{1}{20} = \frac{8}{100} + \frac{5}{100} = \frac{13}{100}\) 7) \(\frac{5}{21} - \frac{3}{14} = \frac{10}{42} - \frac{9}{42} = \frac{1}{42}\) 8) \(\frac{13}{20} - \frac{7}{50} = \frac{65}{100} - \frac{14}{100} = \frac{51}{100}\) 9) \(\frac{4}{17} + \frac{2}{13} = \frac{52}{221} + \frac{34}{221} = \frac{86}{221}\) 10) \(\frac{2}{15} + \frac{3}{20} = \frac{8}{60} + \frac{9}{60} = \frac{17}{60}\) Правый столбец: 1) \(\frac{7}{18} + \frac{1}{27} = \frac{21}{54} + \frac{2}{54} = \frac{23}{54}\) 2) \(\frac{29}{36} + \frac{5}{54} = \frac{87}{108} + \frac{10}{108} = \frac{97}{108}\) 3) \(\frac{23}{30} + \frac{2}{45} = \frac{69}{90} + \frac{4}{90} = \frac{73}{90}\) 4) \(\frac{13}{24} + \frac{17}{36} = \frac{39}{72} + \frac{34}{72} = \frac{73}{72} = 1\frac{1}{72}\) 5) \(\frac{15}{28} + \frac{22}{35} = \frac{75}{140} + \frac{88}{140} = \frac{163}{140} = 1\frac{23}{140}\) 6) \(\frac{4}{21} - \frac{5}{28} = \frac{16}{84} - \frac{15}{84} = \frac{1}{84}\) 7) \(\frac{13}{16} - \frac{19}{24} = \frac{39}{48} - \frac{38}{48} = \frac{1}{48}\) 8) \(\frac{7}{33} - \frac{1}{22} = \frac{14}{66} - \frac{3}{66} = \frac{11}{66} = \frac{1}{6}\) 9) \(\frac{7}{220} + \frac{17}{330} = \frac{21}{660} + \frac{34}{660} = \frac{55}{660} = \frac{1}{12}\) 10) \(\frac{3}{140} + \frac{13}{210} = \frac{9}{420} + \frac{26}{420} = \frac{35}{420} = \frac{1}{12}\)