Giải giúp mik với ạ!!

Đáp án `+` Giải thích các bước giải:

1) `5/12 . 6/11 + 5/12 . 5/11 + 7/12`

`= 5/12 . (6/11 + 5/11) + 7/12`

`= 5/12 . 1 + 7/12`

`= 12/12 = 1.`

2) `6/7 + (-1)/7 . 2/7 + (-1)/7 . 5/7`

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

`= (-1)/7 . 7/7 + 6/7`

`= (-1)/7 + 6/7`

`= 5/7.`

3) `7/19 . (-8)/11 + 7/19 . (-3)/11 - 12/19`

`= 7/19 . ((-8)/11 + (-3)/11) - 12/19`

`= 7/19 . (-11)/11 - 12/19`

`= 7/19 . (-1) - 12/19`

`= -7/19 - 12/19`

`= -19/19 = -1.`

4) `2/13 . 5/9 + 2/13 . 4/9 + 11/13`

`= 2/13 . (5/9 + 4/9) + 11/13`

`= 2/13 . 9/9 + 11/13`

`= 2/13 + 11/13`

`= 13/13 = 1.`

5) `1/3 . 4/5 + 1/3 . 6/5 - 4/3`

`= 1/3 . (4/5 + 6/5) - 4/3`

`= 1/3 . 2 - 4/3`

`= 2/3 - 4/3`

`= -2/3.`

6) `4/19 . (-3)/7 + (-3)/7 . 15/19 + 5/7`

`= (-3)/7 . (4/19 + 15/19) + 5/7`

`= (-3)/7 . 1 + 5/7`

`= 2/7.`