Вопрос:

1) 7 + 8/19; 2) 8/68 + 9; 3) 3 5/16 + 4 7/16; 4) 12 8/13 - 8 4/13; 5) 5 17/21 - 3 8/21 + 4 7/21; 6) 14 8/10 + 5 1/10 - 6 7/10; 2. Вычислите: 1) 6 5/13 + 2 8/13; 2) 5 4/7 + 3 6/7; 3) 1 - 15/19; 4) 8 - 3 4/9; 5) 7 3/8 - 2 5/8; 6) 14 15/32 - 9 19/32.

Ответ:

1. Вычислите:

  1. 1)

    \[ 7 + \frac{8}{19} = \frac{7 \times 19}{19} + \frac{8}{19} = \frac{133}{19} + \frac{8}{19} = \frac{133+8}{19} = \frac{141}{19} \]

  2. 2)

    \[ \frac{8}{68} + 9 = \frac{8}{68} + \frac{9 \times 68}{68} = \frac{8}{68} + \frac{612}{68} = \frac{8+612}{68} = \frac{620}{68} = \frac{155}{17} \]

  3. 3)

    \[ 3 \frac{5}{16} + 4 \frac{7}{16} = (3+4) + (\frac{5}{16} + \frac{7}{16}) = 7 + \frac{5+7}{16} = 7 + \frac{12}{16} = 7 + \frac{3}{4} = 7 \frac{3}{4} \]

  4. 4)

    \[ 12 \frac{8}{13} - 8 \frac{4}{13} = (12-8) + (\frac{8}{13} - \frac{4}{13}) = 4 + \frac{8-4}{13} = 4 + \frac{4}{13} = 4 \frac{4}{13} \]

  5. 5)

    \[ 5 \frac{17}{21} - 3 \frac{8}{21} + 4 \frac{7}{21} = (5-3+4) + (\frac{17}{21} - \frac{8}{21} + \frac{7}{21}) = 6 + \frac{17-8+7}{21} = 6 + \frac{16}{21} = 6 \frac{16}{21} \]

  6. 6)

    \[ 14 \frac{8}{10} + 5 \frac{1}{10} - 6 \frac{7}{10} = (14+5-6) + (\frac{8}{10} + \frac{1}{10} - \frac{7}{10}) = 13 + \frac{8+1-7}{10} = 13 + \frac{2}{10} = 13 + \frac{1}{5} = 13 \frac{1}{5} \]

2. Вычислите:

  1. 1)

    \[ 6 \frac{5}{13} + 2 \frac{8}{13} = (6+2) + (\frac{5}{13} + \frac{8}{13}) = 8 + \frac{5+8}{13} = 8 + \frac{13}{13} = 8 + 1 = 9 \]

  2. 2)

    \[ 5 \frac{4}{7} + 3 \frac{6}{7} = (5+3) + (\frac{4}{7} + \frac{6}{7}) = 8 + \frac{4+6}{7} = 8 + \frac{10}{7} = 8 + 1 \frac{3}{7} = 9 \frac{3}{7} \]

  3. 3)

    \[ 1 - \frac{15}{19} = \frac{19}{19} - \frac{15}{19} = \frac{19-15}{19} = \frac{4}{19} \]

  4. 4)

    \[ 8 - 3 \frac{4}{9} = 7 \frac{9}{9} - 3 \frac{4}{9} = (7-3) + (\frac{9}{9} - \frac{4}{9}) = 4 + \frac{5}{9} = 4 \frac{5}{9} \]

  5. 5)

    \[ 7 \frac{3}{8} - 2 \frac{5}{8} = 6 \frac{11}{8} - 2 \frac{5}{8} = (6-2) + (\frac{11}{8} - \frac{5}{8}) = 4 + \frac{11-5}{8} = 4 + \frac{6}{8} = 4 + \frac{3}{4} = 4 \frac{3}{4} \]

  6. 6)

    \[ 14 \frac{15}{32} - 9 \frac{19}{32} = 13 \frac{32+15}{32} - 9 \frac{19}{32} = 13 \frac{47}{32} - 9 \frac{19}{32} = (13-9) + (\frac{47}{32} - \frac{19}{32}) = 4 + \frac{47-19}{32} = 4 + \frac{28}{32} = 4 + \frac{7}{8} = 4 \frac{7}{8} \]