làm câu 7 8 9 giúp mình với ạ

Đáp án:

`7)|x+1/3|=0`

`=>x+1/3=0`

`=>x=0-1/3`

`=>x=-1/3`

Vậy: `x=-1/3`

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`8)|x+3/4|=1/2`

`=>x+3/4 = 1/2` hoặc `-1/2`

`th_1:x+3/4=1/2`

`x=1/2-3/4`

`x=2/4-3/4`

`x=-1/4`

`th_2:x+3/4=-1/2`

`x=(-1/2)-3/4`

`x=(-2/4)-3/4`

`x=-5/4`

Vậy: `x in {-1/4;-5/4}`

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`9)|x+3/4|-1/3=0`

`=>|x+3/4|=0+1/3`

`=>|x+3/4|=1/3`

`=>x+3/4=1/3` hoặc `-1/3`

`th_1:x+3/4=1/3`

`x=1/3-3/4`

`x=4/12 - 9/12`

`x=-5/12`

`th_2:x+3/4=-1/3`

`x=(-1/3)-3/4`

`x=(-4/12)-9/12`

`x=-13/12`

Vậy: `x in {-5/12;-13/12}`