a) 31/6+ ( 1- 7/6).

b) ( 2021/2022 + 3/5 + -2021/2022): 1 2/5

c) 9/17 nhân 8/5 - 9/17 nhân 3/5 + 8/17. d) 3 nhân ( 32,1 - 6,32) + 7 nhân 32,1 + 3 nhân 0,32.

Bài 2: a) x - 1/-2 = -18/x - 1. b) 4/7 nhân x + 2/4 = -1/5

`a) 31/6 + (1 -7/6)`

`= 31/6 + 1 -7/6`

`= ( 31/6 - 7/6) + 1`

`= 4 +1`

`=5`

`b) ( 2021/2022 + 3/5 + -2021/2022): 1 2/5`

`= [2021/2022 +(-2021/2022)+3/5] : 7/5`

`= 3/5 .5/7`

`= 3/7`

`c) 9/17 × 8/5 - 9/17 × 3/5 + 8/17.`

`= 9/17 × ( 8/5 - 3/5 ) + 8/17`

`= 9/17 × 1 + 8/17`

`= 1`

`d) 3 × ( 32,1 - 6,32) + 7 × 32,1 + 3 × 0,32.`

`= 3 × ( 32,1 - 6,32+0,32) + 7 × 32,1`

`= 3 × 26,4 + 7 × 32,1`

`= 78,3 + 224.7`

`= 303`

Bài `2`

`a) x - 1/-2 = -18/x - 1`

` => (x+1).(x+1) = -2 . (-18)`

`=> (x+1)^2 = 36 = 6^2`

`@` TH1

`=> x + 1 = 6`

`=> x = 6 -1`

`=> x = 5`

`@` TH2:

`=> x + 1 = -6`

`=> x = -6 - 1`

`=> x = -7`

`b) 4/7. x + 2/4 = -1/5`

`     4/7.x           = -1/5 - 2/4`

`           x           = -7/10 : 4/7`

`           x            =-49/40`