giúppppppppppppppppppppppppppppppppppppp

Lời giải:

7a)

`101/102=(102-1)/102=1-1/102`

`202/203=(203-1)/203=1-1/203`

Vì `1/102>1/203`

`=>1-1/102<1-1/203`

`=>101/102<202/203`

Vậy `101/102<202/203`

7b)

`2019/2020=(2020-1)/2020=1-1/2020`

`2020/2021=(2021-1)/2021=1-1/2021`

Vì `1/2020>1/2021`

`=>1-1/2020<1-1/2021`

`=>2019/2020<2020/2021`

Vậy `2019/2020<2020/2021`

7c)

`(-2020)/2019=(-2019-1)/2019=-1-1/2019`

`(-2021)/2020=(-2020-1)/2020=-1-1/2020`

Vì `1/2019>1/2020`

`=>-1/2019< -1/2020`

`=>-1-1/2019< -1-1/2020`

8a)

`1234/1235=(1235-1)/(1235)=1-1/1235`

`4319/4320=(4320-1)/4320=1-1/4320`

Vì `1/1235>1/4320`

`=>1-1/1235<1-1/4320`

`=>1234/1235<4319/4320`

Vậy `1234/1235<4319/4320`

8b)

`2012/2002=(2002+10)/2002=1+10/2002`

`2022/2012=(2012+10)/2012=1+10/2012`

Vì `10/2002>10/2012`

`=>1+10/2002>1+10/2012`

`=>2012/2002>2022/2012`

Vậy `2012/2002>2022/2012`

8c)

`9/100<99/100=(100-1)/100=1-1/100`

`100/101=(101-1)/101=1-1/101`

Vì `1/100>1/101`

`=>1-1/100<1-1/101`

`=>99/100<100/101`

`=>9/100<100/101`

Vậy `9/100<100/101`