Вопрос:

40. Вычислите и запишите ответ: 1) \(\frac{1}{9}+\frac{1}{27}\); 2) \(\frac{38}{49}-\frac{3}{7}\); 3) \(\frac{2}{3}+\frac{1}{9}\); 4) \(\frac{7}{8}+\frac{1}{2}\); 5) \(\frac{5}{7}-\frac{1}{2}\); 6) \(\frac{5}{6}-\frac{3}{5}\); 7) \(\frac{1}{9}-\frac{1}{27}\); 8) \(\frac{8}{9}-\frac{2}{7}\); 9) \(\frac{7}{8}-\frac{1}{2}\); 10) \(\frac{5}{26}+\frac{1}{6}\); 11) \(\frac{1}{10}-\frac{1}{11}\); 12) \(\frac{1}{3}+\frac{1}{7}\); 13) \(\frac{2}{7}+\frac{7}{9}\); 14) \(\frac{1}{2}+\frac{1}{8}\); 15) \(\frac{3}{5}+\frac{5}{6}\); 16) \(\frac{1}{2}-\frac{1}{8}\); 17) \(\frac{1}{12}+\frac{1}{3}\); 18) \(\frac{8}{9}-\frac{7}{8}\).

Ответ:

  1. \(\frac{1}{9}+\frac{1}{27}=\frac{3}{27}+\frac{1}{27}=\frac{4}{27}\).
  2. \(\frac{38}{49}-\frac{3}{7}=\frac{38}{49}-\frac{21}{49}=\frac{17}{49}\).
  3. \(\frac{2}{3}+\frac{1}{9}=\frac{6}{9}+\frac{1}{9}=\frac{7}{9}\).
  4. \(\frac{7}{8}+\frac{1}{2}=\frac{7}{8}+\frac{4}{8}=\frac{11}{8}=1\frac{3}{8}\).
  5. \(\frac{5}{7}-\frac{1}{2}=\frac{10}{14}-\frac{7}{14}=\frac{3}{14}\).
  6. \(\frac{5}{6}-\frac{3}{5}=\frac{25}{30}-\frac{18}{30}=\frac{7}{30}\).
  7. \(\frac{1}{9}-\frac{1}{27}=\frac{3}{27}-\frac{1}{27}=\frac{2}{27}\).
  8. \(\frac{8}{9}-\frac{2}{7}=\frac{56}{63}-\frac{18}{63}=\frac{38}{63}\).
  9. \(\frac{7}{8}-\frac{1}{2}=\frac{7}{8}-\frac{4}{8}=\frac{3}{8}\).
  10. \(\frac{5}{26}+\frac{1}{6}=\frac{15}{78}+\frac{13}{78}=\frac{28}{78}=\frac{14}{39}\).
  11. \(\frac{1}{10}-\frac{1}{11}=\frac{11}{110}-\frac{10}{110}=\frac{1}{110}\).
  12. \(\frac{1}{3}+\frac{1}{7}=\frac{7}{21}+\frac{3}{21}=\frac{10}{21}\).
  13. \(\frac{2}{7}+\frac{7}{9}=\frac{18}{63}+\frac{49}{63}=\frac{67}{63}=1\frac{4}{63}\).
  14. \(\frac{1}{2}+\frac{1}{8}=\frac{4}{8}+\frac{1}{8}=\frac{5}{8}\).
  15. \(\frac{3}{5}+\frac{5}{6}=\frac{18}{30}+\frac{25}{30}=\frac{43}{30}=1\frac{13}{30}\).
  16. \(\frac{1}{2}-\frac{1}{8}=\frac{4}{8}-\frac{1}{8}=\frac{3}{8}\).
  17. \(\frac{1}{12}+\frac{1}{3}=\frac{1}{12}+\frac{4}{12}=\frac{5}{12}\).
  18. \(\frac{8}{9}-\frac{7}{8}=\frac{64}{72}-\frac{63}{72}=\frac{1}{72}\).

Ответ: \(\frac{4}{27};\ \frac{17}{49};\ \frac{7}{9};\ 1\frac{3}{8};\ \frac{3}{14};\ \frac{7}{30};\ \frac{2}{27};\ \frac{38}{63};\ \frac{3}{8};\ \frac{14}{39};\ \frac{1}{110};\ \frac{10}{21};\ 1\frac{4}{63};\ \frac{5}{8};\ 1\frac{13}{30};\ \frac{3}{8};\ \frac{5}{12};\ \frac{1}{72}\).