giúp mình với . minh cảm ơn

Đáp án:

 

Giải thích các bước giải:

 `a) 2017. (2016- 2020)+ 4. 2017+ 2018`

`= 2017. (-4)+ 4. 2017+ 2018`

`= 2017. [(-4)+ 4]+ 2018`

`= 2017. 0+ 2018`

`= 0+ 2018`

`= 2018`

`b) 5/20+ -1/4`

`= 5/20+ (-5/20)`

`= 0`

`c) 5/10+ 21/28+ 60/72`

`= 1/2+ 3/4+ 5/6`

`= 6/12+ 9/12+ 10/12`

`= (6+ 9+ 10)/12`

`= 25/12`

`d) -1 1/2: 7/13+ 1 1/2: -6/13`

`= 1 1/2: (-7/13)+ 1 1/2: -6/13`

`= 1 1/2: [(-7/13)+ (-6/13)]`

`= 3/2: (-1)`

`= 3/2. (-1)`

`= -3/2`

`a) x- 25= 12- (x+ 1)`

`x- 25= 12- x- 1`

`x- 25= 11- x`

`x- 25= -x+ 11`

`x- 25+ 25= -x+ 11+ 25`

`x= -x+ 36`

`x+ x= -x+ 36+ x`

`2x= 36`

`x= 36: 2`

`x= 18`

`b) x/2= -5/10`

`→ x. 10= 2. (-5)`

`x. 10= -10`

`x= -10: 10`

`x= -1`

`c) x/3- 1/7= 6/7`

`x/3= 6/7+ 1/7`

`x/3= 1`

`→ x. 1= 3`

`x= 3: 1`

`x= 3`