giải cho toi bài tâp trên

Đáp án + Giải thích các bước giải:

Bài `4`:

`1) 4/3 + 3/5 + 7/3 + 2/5 + 1/3`

`= (4/3 + 7/3 + 1/3) + (3/5 + 2/5)`

`= 12/3 + 5/5`

`= 4 + 1`

`= 5`

`2) 4/7 + 3/4 + 2/7 + 5/4 + 1/7`

`= (4/7 + 2/7 + 1/7) + (3/4 + 5/4)`

`= 7/7 + 8/4`

`= 1 + 2`

`= 3`

`3) -3/4 + 2/7 + -1/4 + 3/5 + 5/7`

`= (-3/4 + -1/4) + (2/7 + 5/7) + 3/5`

`= -4/4 + 7/7 + 3/5`

`= -1 + 1 + 3/5`

`= 3/5`

`4) -2/5 + 3/-4 + 6/7 + 3/4 + 2/5`

`= (-2/5 + 2/5) + (-3/4 + 3/4) + 6/7`

`= 0 + 0 + 6/7`

`= 6/7`

`5) -5/7 + 3/4 + -1/5 + -2/7 + 1/4`

`= (-5/7 + -2/7) + (3/4 + 1/4) + (-1/5)`

`= -7/7 + 4/4 + (-1/5)`

`= -1 + 1 + (-1/5)`

`= -1/5`

`6) -1/8 + 7/9 + -7/9 + 6/7 + 2/14`

`= -1/8 + (7/9 + -7/9) + (6/7 + 2/14)`

`= -1/8 + (12/14 + 2/14)`

`= -1/8 + 14/14`

`= -1/8 + 1`

`= 7/8`

`7) -5/9 + 8/15 + -2/11 + 4/-9 + 7/15`

`= (-5/9 + -4/9) + (8/15 + 7/15) + (-2/11)`

`= -9/9 + 15/15 + (-2/11)`

`= -1 + 1 + (-2/11)`

`= -2/11`

`8) 10/17 - 5/13 - (-7/17) - 8/13 + 11/25`

`= (10/17 + 7/17) + (-5/13 - 8/13) + 11/25`

`= 17/17 + -13/13 + 11/25`

`= 1 + -1 + 11/25`

`= 11/25`

`9) -2/17 + 15/23 + -15/17 + 4/19 + 8/23`

`= (-2/17 - 15/17) + (15/23 + 8/23) + 4/19`

`= -17/17 + 23/23 + 4/19`

`= -1 + 1 + 4/19`

`= 4/19`