Question

#662. 5 класс. С действиями.

Answer 1

a) $( frac{7}{15} - frac{1}{6} )+ frac{2}{5}$
1) $frac{7}{15} - frac{1}{6}= frac{7*2}{30} -frac{1*5}{30}=frac{14}{30}-frac{5}{30}=frac{8}{30}=frac{2*2}{2*15}=frac{4}{15}$
2) $frac{4}{15}+ frac{2}{5}= frac{4}{15}+ frac{2*3}{15}=frac{4}{15}+frac{6}{15}=frac{10}{15}=frac{2*5}{3*5}=frac{2}{3}$

б) $( frac{3}{8} - frac{1}{9} )+ frac{25}{36}$
1) $frac{3}{8} - frac{1}{9} =frac{3*9}{72} - frac{1*8}{72} =frac{27}{72} - frac{8}{72}= frac{19}{72}$
2) $frac{19}{72}+ frac{25}{36}= frac{19}{72}+ frac{25*2}{72} = frac{19}{72}+ frac{50}{72}= frac{69}{72}$

в) $( frac{8}{9} - frac{5}{6} )+ frac{2}{3}$
1) $frac{8}{9} - frac{5}{6}=frac{8*2}{18} - frac{5*3}{18}=frac{16}{18} - frac{15}{18}=frac{1}{18}$
2) $frac{1}{18} + frac{2}{3}=frac{1}{18} + frac{2*6}{18}=frac{1}{18} + frac{12}{18}=frac{13}{18}$

г)  $( frac{7}{8} - frac{13}{20} )+ frac{9}{10}$
1) $frac{7}{8} - frac{13}{20} =frac{7*5}{40} - frac{13*2}{40} =frac{35}{40} - frac{26}{40}=frac{9}{40}$
2) $frac{9}{40}+frac{9}{10}=frac{9}{40}+frac{9*4}{40}=frac{9}{40}+frac{36}{40}=frac{45}{40}=1frac{5}{40}=1frac{1*5}{5*8}=1frac{1}{8}$

д) $( frac{7}{18} + frac{1}{12} )+ frac{5}{6}$
1) $frac{7}{18} + frac{1}{12}= frac{7*2}{36} + frac{1*3}{36} =frac{14}{36} + frac{3}{36}= frac{17}{36}$
2) $frac{17}{36}+ frac{5}{6}= frac{17}{36}+ frac{5*6}{36}=frac{17}{36}+ frac{30}{36}=frac{47}{36}=1 frac{11}{36}$

е)  $( frac{3}{4} - frac{8}{15} )+ frac{17}{20}$
1) $frac{3}{4} - frac{8}{15}= frac{3*15}{60} - frac{8*4}{60}=frac{45}{60} - frac{32}{60}=frac{13}{60}$
2) $frac{13}{60}+ frac{17}{20}= frac{13}{60}+ frac{17*3}{60}=frac{13}{60}+ frac{51}{60}= frac{64}{60}= 1frac{4}{60}=1frac{4}{4*15}=1frac{1}{15}$