Đáp án:
._.
Giải thích các bước giải:
`a) x+3 vdots x`
`=> 3 vdots x`
`=> x in Ư(3)`
`=> x in {-3;-1;1;3}`
`b) 6x+4 vdots 2x-1`
`=> 3(2x-1)+7 vdots 2x-1`
Mà `3(2x-1) vdots 2x-1`
`=> 7 vdots 2x-1`
`=> 2x-1 in Ư(7)={-7;-1;1;7}`
`=> 2x in {-6;0;2;8}`
`=> x in {-3;0;1;4}`
`c) x^2-x+7 vdots x-1`
`=> x(x-1)+7 vdots x-1`
Mà `x(x-1) vdots x-1`
`=> 7 vdots x-1`
`=> x-1 in Ư(7)={-7;-1;1;7}`
`=> x in {-6;0;2;8}`