Answers

1. `1` 

   `3/5 . 1/7 + 3/5 . 7/6 – 2/5`

   `= 3/5×(1/7+6/7)-2/5`

   `= 3/5×1-2/5=1/5`

   `2` 

   `2/3 . 1/9 + 2/3 . 8/9 – 5/3`

   `=2/3×(1/9+8/9) – 5/3`

   `=2/3×1-5/3=-3/3=-1`

   `3` 

   `1/2 – 5/2 + -7/10`

   `=-4/2-7/10`

   `=-20/10-7/10=-27/10`

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2. Đáp án:

   `a)` `27/70`

   `b)` `-1`

   `c)` `(-27)/10`

   Giải thích các bước giải:

   `a)` `3/5*1/7+3/5*7/6-2/5`

   `=3/5*(1/7+7/6)-2/5`

   `=3/5*55/42-2/5`

   `=11/14-2/5`

   `=27/70`

   —————–

   `b)` `2/3 * 1/9 + 2/3 * 8/9 – 5/3  `

   `=2/3*(1/9+8/9)-5/3`

   `=2/3-5/3`

   `=-1`

   —————–

   `c)` `1/2 – 5/2 + -7/10`

   `=1/2-5/2-7/10`

   `=(-2)-7/10`

   `=(-27)/10`

   Reply