Проверочная работа №2. 1. Вычислите: а) \frac{3}{4} + \frac{4}{5}; б) \frac{2}{13} + 0; г) \frac{5}{9} + \frac{2}{11}; д) \frac{12}{4} + \frac{1}{3}; е) \frac{5}{6} + \frac{7}{8}

а) \frac{3}{4} + \frac{4}{5} = \frac{3*5}{4*5} + \frac{4*4}{5*4} = \frac{15}{20} + \frac{16}{20} = \frac{31}{20} = 1\frac{11}{20}. б) \frac{2}{13} + 0 = \frac{2}{13}. г) \frac{5}{9} + \frac{2}{11} = \frac{5*11}{9*11} + \frac{2*9}{11*9} = \frac{55}{99} + \frac{18}{99} = \frac{73}{99}. д) \frac{12}{4} + \frac{1}{3} = 3 + \frac{1}{3} = \frac{9}{3} + \frac{1}{3} = \frac{10}{3} = 3\frac{1}{3}. е) \frac{5}{6} + \frac{7}{8} = \frac{5*4}{6*4} + \frac{7*3}{8*3} = \frac{20}{24} + \frac{21}{24} = \frac{41}{24} = 1\frac{17}{24}.