а) \(\frac{1}{5}+\frac{1}{7}=\frac{7}{35}+\frac{5}{35}=\frac{12}{35}\);
б) \(\frac{1}{3}+\frac{2}{7}=\frac{7}{21}+\frac{6}{21}=\frac{13}{21}\);
в) \(\frac{3}{5}+\frac{5}{6}=\frac{18}{30}+\frac{25}{30}=\frac{43}{30}=1\frac{13}{30}\);
г) \(\frac{8}{9}-\frac{2}{5}=\frac{40}{45}-\frac{18}{45}=\frac{22}{45}\). Проверка: \(\frac{22}{45}+\frac{2}{5}=\frac{22}{45}+\frac{18}{45}=\frac{8}{9}\);
д) \(\frac{5}{12}+\frac{1}{6}=\frac{5}{12}+\frac{2}{12}=\frac{7}{12}\);
е) \(\frac{3}{5}-\frac{4}{15}=\frac{9}{15}-\frac{4}{15}=\frac{1}{3}\). Проверка: \(\frac{1}{3}+\frac{4}{15}=\frac{5}{15}+\frac{4}{15}=\frac{3}{5}\);
ж) \(\frac{19}{21}-\frac{11}{15}=\frac{95}{105}-\frac{77}{105}=\frac{6}{35}\). Проверка: \(\frac{19}{21}-\frac{6}{35}=\frac{95}{105}-\frac{18}{105}=\frac{11}{15}\);
з) \(\frac{5}{42}+\frac{10}{63}=\frac{15}{126}+\frac{20}{126}=\frac{5}{18}\);
и) \(\frac{11}{21}+\frac{2}{26}=\frac{11}{21}+\frac{1}{13}=\frac{143}{273}+\frac{21}{273}=\frac{164}{273}\);
к) \(\frac{5}{24}-\frac{7}{60}=\frac{25}{120}-\frac{14}{120}=\frac{11}{120}\). Проверка: \(\frac{5}{24}-\frac{11}{120}=\frac{25}{120}-\frac{11}{120}=\frac{7}{60}\).

Поделись с друзьями