Question

Tìm n thuộc Z sao cho 2n - 3 : n + 1

giup mik với

Answer 1

2n-3 \(⋮\)  n+1

=> 2n+2-5 \(⋮\)  n+1

=> 2(n+1)-5  \(⋮\) n+1

Mà 2(n+1) \(⋮\) n+1

=> 5 \(⋮\) n+1

=> n+1 ∈ Ư(5)

mà Ư(5) ∈ {1;-1;5;-5}

⇒ n+1 ∈ {1;-1;5;-5}

TH1: n+1=1 => n=0 ∈ Z

TH2: n+1=-1 => n=-2 ∈ Z

TH3: n+1=5 => n= 4 ∈ Z

TH4: n+1=-5 => n= -6∈ Z

=> n ∈ {0;-2;4;6}

 

Answer 2

`(2n-3) vdots (n+1)`

`-> (2n+2)-3 vdots (n+1)`

`-> -3 vdots (n+1)`

`-> n+1 \in {-3;3;-1;1}`

`-> n \in {-4;2;-2;0}`.

Answer 3

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