Вопрос:

1033. Выполните умножение: 1) -12 · 5; 5) -\frac{15}{16} · (-\frac{48}{55}); 9) 45 · (-\frac{8}{15}); 2) -0,4 · 1,5; 6) -\frac{13}{24} · \frac{16}{39}; 10) \frac{16}{17} · (-\frac{6}{8}); 3) 3,4 · (-1,8); 7) \frac{6}{35} · (-\frac{14}{15}); 11) -3\frac{5}{9} · (-5\frac{1}{4}); 4) -\frac{3}{4} · (-\frac{5}{6}); 8) -\frac{7}{12} · 24; 12) -1\frac{5}{7} · 6\frac{1}{8}; 1034. Выполните умножение: 1) 16 · (-3); 5) -\frac{4}{7} · \frac{7}{9}; 2) -8 · (-7); 6) -6 · (-\frac{5}{24});

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Ответ:

Краткое пояснение: Чтобы умножить дроби, нужно перемножить их числители и знаменатели, предварительно определив знак результата.
  1. -12 ⋅ 5 = -60

  2. -0,4 ⋅ 1,5 = -0,6

  3. 3,4 ⋅ (-1,8) = -6,12

  4. -\frac{3}{4} ⋅ (-\frac{5}{6}) = \frac{3 ⋅ 5}{4 ⋅ 6} = \frac{15}{24} = \frac{5}{8}

  5. -\frac{15}{16} ⋅ (-\frac{48}{55}) = \frac{15 ⋅ 48}{16 ⋅ 55} = \frac{3 ⋅ 3}{1 ⋅ 11} = \frac{9}{11}

  6. -\frac{13}{24} ⋅ \frac{16}{39} = -\frac{13 ⋅ 16}{24 ⋅ 39} = -\frac{1 ⋅ 2}{3 ⋅ 3} = -\frac{2}{9}

  7. \frac{6}{35} ⋅ (-\frac{14}{15}) = -\frac{6 ⋅ 14}{35 ⋅ 15} = -\frac{2 ⋅ 2}{5 ⋅ 5} = -\frac{4}{25}

  8. -\frac{7}{12} ⋅ 24 = -\frac{7 ⋅ 24}{12} = -7 ⋅ 2 = -14

  9. 45 ⋅ (-\frac{8}{15}) = -\frac{45 ⋅ 8}{15} = -3 ⋅ 8 = -24

  10. \frac{16}{17} ⋅ (-\frac{6}{8}) = -\frac{16 ⋅ 6}{17 ⋅ 8} = -\frac{2 ⋅ 6}{17 ⋅ 1} = -\frac{12}{17}

  11. -3\frac{5}{9} ⋅ (-5\frac{1}{4}) = -\frac{32}{9} ⋅ (-\frac{21}{4}) = \frac{32 ⋅ 21}{9 ⋅ 4} = \frac{8 ⋅ 7}{3 ⋅ 1} = \frac{56}{3} = 18\frac{2}{3}

  12. -1\frac{5}{7} ⋅ 6\frac{1}{8} = -\frac{12}{7} ⋅ \frac{49}{8} = -\frac{12 ⋅ 49}{7 ⋅ 8} = -\frac{3 ⋅ 7}{1 ⋅ 2} = -\frac{21}{2} = -10\frac{1}{2}

1034. Выполните умножение:

  1. 16 ⋅ (-3) = -48

  2. -8 ⋅ (-7) = 56

  3. -\frac{4}{7} ⋅ \frac{7}{9} = -\frac{4 ⋅ 7}{7 ⋅ 9} = -\frac{4}{9}

  4. -6 ⋅ (-\frac{5}{24}) = \frac{6 ⋅ 5}{24} = \frac{1 ⋅ 5}{4} = \frac{5}{4} = 1\frac{1}{4}

Ответ: См. решение

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