Tính 19/4 x 12/7 13/6 : 26/15 3 x 2 2/9 : 5 2 2/9 là hỗn số

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1. Đáp án:

    

   Giải thích các bước giải:

   * `19/4 × 12/7`

   `= (19 × 12)/(4 × 7)`

   `= (19 × 4 × 3)/(4 × 7)`

   `= 57/7`

   * `13/6 : 26/15`

   `= 13/6 × 15/26`

   `= (13 × 15)/(6 × 26)`

   `= (13 × 3 × 5)/(3 × 2 × 13 × 2)`

   `= 5/4`

   * `3 × 2 2/9 : 5`

   `= 3 × 20/9 × 1/5`

   `= (3 × 20 × 1)/(9 × 5)`

   `= (3 × 5 × 4 × 1)/(3 × 3 × 5)`

   `= 4/3`

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2. a) $\dfrac{19}{4}.\dfrac{12}{7}$

   $=\dfrac{19.12}{4.7}$

   $=\dfrac{19.3}{7}=\dfrac{57}{7}$

   b) $\dfrac{13}{6}:\dfrac{26}{15}$

   $=\dfrac{13}{6}.\dfrac{15}{26}$

   $=\dfrac{13.15}{6.26}$

   $=\dfrac{5}{2.2}=\dfrac{5}{4}$

   c) $3.2\dfrac{2}{9}:5$

   $=3.\dfrac{20}{9}.\dfrac{1}{5}$

   $=\dfrac{1.20.1}{3.5}$

   $=\dfrac{4}{3}$

   d) $2\dfrac{2}{9}$

   $=\dfrac{2.9+2}{9}$

   $=\dfrac{20}{9}$

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