Đáp án:
._.
Giải thích các bước giải:
`a) x+8 vdots x+7`
`=> x+7+1 vdots x+7`
`=> 1 vdots x+7`
`=> x+7 in Ư(1)={-1;1}`
`=> x in {-8;-6}`
`b) 2x-9 vdots x-5`
`=> 2x-10+1 vdots x-5`
`=> 2(x-5)+1 vdots x-5`
Mà `2(x-5) vdots x-5`
`=> 1 vdots x-5`
`=> x-5 in Ư(1)={-1;1}`
`=> x in {4;6}`
`c) 2x^2+3x+2 vdots x+1`
`=> 2x^2+2x+x+2 vdots x+1`
`=> 2x(x+1)+x+2 vdots x+1`
Mà `2x(x+1) vdots x+1`
`=> x+2 vdots x+1`
`=> x+1+1 vdots x+1`
`=> 1 vdots x+1`
`=> x+1 in Ư(1)={-1;1}`
`=> x in {-2;0}`
