a) x-1 chia hết cho x+1 b) 5x-2 chia hết cho x+3 c) 3x+5 chia hết cho 2x-1

`text{Đáp án + Giải thích các bước giải:}`

`a, x-1 vdots x+1`

`=> x+1-2 vdots x+1`

`=> (x+1)-2 vdots x+1`

`=> -2 vdots x+1`

`=> x+1 in Ư_(-2)`

`=> x+1 in {-2;-1;1;2}`

`=> x in {-3;-2;0;1}`

`b, 5x-2 vdots x+3`

`=> 5x+15-17 vdots x+3`

`=> 5(x+3)-17 vdots x+3`

`=> -17 vdots x+3`

`=> x+3 in Ư_(-17)`

`=> x+3 in {-17;-1;1;17}`

`=> x in {-20;-4;-2;14}`

`c, 3x+5 vdots 2x-1`

`=> 2(3x+5) vdots 2x-1`

`=> 6x+10 vdots 2x-1`

`=> 6x-3+13 vdots 2x-1`

`=> 3(2x-1)+13 vdots 2x-1`

`=> 13 vdots 2x-1`

`=> 2x-1 in Ư_13`

`=> 2x-1in{-13;-1;1;13}`

`=> 2x in {-12;0;2;14}`

`=> x in {-6;0;1;7}`