Đáp án:
$@kun$
Bài 1 :
`a) 27x=-81`
`=>x=-81:27`
`=>x=-3`
`b)7|x|=56`
`=>x=56:7`
`=>x=8`
Vậy `x = 8` hoặc `x = -8`
Bài 2 :
`a)` Nếu `x vdots 6`
`=>x in Ư(6)={±1;±2;±3;±6}`
`=>x in{±1;±2;÷3;±6}`
Nếu `6 vdots x`
`=>x in B(6)={±0;±6;±12;±18;±24;.....}`
`=> x in {±0;±6;±12;±18;±14;....}`
`b) (x+8) vdots (x+1)`
`=> (x+1) vdots (x+1)`
`=> (x+8)-(x+1) vdots (x+1)`
`=> 7 vdots (x+1)`
`=> (x+1) in Ư(7)={±1;±7}`
`TH1 : x+1=1=>x=0`
`TH2 : x+1=-1=>x=-2`
`TH3 : x+1=7=>x=6`
`TH4 : x+1=-7=>x=-8`
`=> x in {0;-2;6;-8}`
`c) 9 vdots x+1`
`=> x+1 in Ư(9)={±1;±3;±9}`
`=>x in {0;-2;2;-4;8;-10}`
Giải thích các bước giải:
