Question

n + 4 chia hết cho 2n +3 .

Answer 1

`n+4 vdots 2n+3`

`=> 2(n+4) vdots 2n+3`

`=>2n+8 vdots 2n+3`

`=>2n+3+5 vdots 2n+3`

`=>(2n+3)+5 vdots 2n+3`

mà `2n+3 vdots 2n+3`

Nên `5 vdots 2n+3`

`=>2n+3 in Ư(5)={+-1;+-5}`

`=>2n in {-2;-4;2;-8}`

`=>n in {-1;-2;1;-4}`

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