a,3/7x - 2/3x = 10/21 b,7/35 : ( x - 3/1 ) = -2/5 c,|2x - 4|+1 = 5 d,3.|3-2x|- 1 = 2/5 e,3(x-1/2)-5(x+3/5)=-x+1/5 f, (2x-1)(x+2/3)=0

Đáp án+Giải thích các bước giải:

`a)`

`3/7x-2/3x=10/21`

`=>(3/7-2/3)x=10/21`

`=>(9/21-14/21)x=10/21`

`=>-5/21x=10/21`

`=>x=10/21:(-5/21)`

`=>x=10/21.(-21)/5`

`=>x=-2`

Vậy `x=-2`

`b)`

`7/35:(x-3/1)=(-2)/5`

`=>1/5:(x-3)=-2/5`

`=>x-3=1/5:(-2/5)`

`=>x-3=1/5 .(-5)/2`

`=>x-3=-1/2`

`=>x=-1/2+3`

`=>x=-1/2+6/2`

`=>x=5/2`

Vậy `x=5/2`

`c)`

`|2x-4|+1=5`

`=>|2x-4|=5-1`

`=>|2x-4|=4`

Th1: `2x-4=4`

`=>2x=4+4`

`=>2x=8`

`=>x=8/2`

`=>x=4`

Th2: `2x-4=-4`

`=>2x=-4+4`

`=>2x=0`

`=>x=0/2`

`=>x=0`

Vậy `x\in{4;0}`

`d)`

`3.|3-2x|-1=2/5`

`=>3.|3-2x|=2/5+1`

`=>3.|3-2x|=2/5+5/5`

`=>3.|3-2x|=7/5`

`=>|3-2x|=7/5:3`

`=>|3-2x|=7/5 . 1/3`

`=>|3-2x|=7/15`

Th1: `3-2x=7/15`

`=>2x=3-7/15`

`=>2x=45/15-7/15`

`=>2x=38/15`

`=>x=38/15:2`

`=>x=38/15 . 1/2`

`=>x=19/15`

Th2: `3-2x=-7/15`

`=>2x=3+7/15`

`=>2x=45/15+7/15`

`=>2x=52/15`

`=>x=52/15:2`

`=>x=52/15 . 1/2`

`=>x=26/15`

Vậy `x\in{19/15;26/15}`

`e)`

`3(x-1/2)-5(x+3/5)=-x+1/5`

`=>3x-3/2-5x-3=-x+1/5`

`=>3x-5x+x=1/5+3/2+3`

`=>-x=2/10+15/10+30/10`

`=>-x=47/30`

`=>x=-47/30`

Vậy `x=-47/30`

`f)`

`(2x-1)(x+2/3)=0`

`=>2x-1=0` hoặc `x+2/3=0`

`=>2x=1` hoặc `x=-2/3`

`=>x=1/2` hoặc `x=-2/3`

Vậy `x\in{1/2;-2/3}`

`#ld`