Законы сложения. а)1/27+ 5/9+1/3 б)2/9+5/6+1/18 в)2/15+1/5+3/10 г)3/8+5/12+1/24 д)1/4+3/8+5/16 е)5/7+3/14+2/21 вычислите: а) 1/5+3/4+1/5+1/4 б)11/12+7/10+3/100+1/12 в)12/17+15/24+3/8+5/16 г)3/7+5/9+4/9+4/7 30 !

Ответы

Maксим56 03.10.2020 08:40

Номер 1

$\frac{1}{27} + \frac{5}{9} + \frac{1}{3} =\\= \frac{1}{27} + \frac{15}{27} + \frac{9}{27} =\\= \frac{1+15+9}{27} = \frac{25}{27} \\\\ \frac{2}{9} + \frac{5}{6} + \frac{1}{18} =\\= \frac{4}{18} + \frac{15}{18} + \frac{1}{18} =\\= \frac{4+15+1}{18} = \frac{20}{18}=1 \frac{2}{18}=1 \frac{1}{9} \\\\ 
\frac{2}{15} + \frac{1}{5} + \frac{3}{10} =\\= \frac{4}{30} + \frac{6}{30} + \frac{9}{30} =\\= \frac{4+6+9}{30} = \frac{19}{30}$

$\frac{3}{8} + \frac{5}{12} + \frac{1}{24} =\\= \frac{9}{24} + \frac{10}{24} + \frac{1}{24} =\\= \frac{20}{24} = \frac{5}{6} \\\\ \frac{1}{4} + \frac{3}{8} + \frac{5}{16}=\\= \frac{4+6+5}{16} = \frac{15}{16} \\\\ \frac{5}{7} + \frac{3}{14} + \frac{2}{21} =\\= \frac{30+9+4}{42} = \frac{43}{42} =1 \frac{1}{42}$

Номер 2

$\frac{1}{5} + \frac{3}{4} + \frac{1}{5} + \frac{1}{4} = \frac{4+15+4+5}{20} = \frac{28}{20} = 1\frac{2}{5} \\\\ \frac{11}{12} + \frac{7}{10} + \frac{3}{100} + \frac{1}{12} = \frac{275+210+9+25}{300} = \frac{519}{300}= \frac{173}{100} \\$

$\frac{12}{17} + \frac{15}{24} + \frac{3}{8} + \frac{5}{16}= \frac{12}{17} + \frac{15}{24} + \frac{11}{16}= \frac{12}{17} + \frac{63}{48}= \frac{576+1071}{816} = \frac{1647}{816}=2 \frac{15}{816}=\\=2 \frac{5}{272} \\\\
\frac{3}{7} + \frac{5}{9} + \frac{4}{9} + \frac{4}{7} = \frac{27+35+28+36}{63} = \frac{126}{63} =2$