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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 6: Tìm n cho biết N+3 chia hết cho n-1

Toán Lớp 6: Tìm n cho biết
N+3 chia hết cho n-1

Comments ( 2 )

  1. $n$ $+$ $3$ $\vdots$ $n$ $-$ $1$
    $\text{⇒  ($n$ $-$ 1) + 4 $\vdots$ $n$ $-$ 1}$
    $\text{Vì $n$ $-$ 1 $\vdots$ $n$ $-$ 1}$
    $\text{⇒ 4 $\vdots$ $n$ $-$ 1}$
    $\text{⇒ $n$ $-$ 1 ∈ Ư(4) = {± 1 ; ±2 ; ±4} }$
    $\text{⇒ $n$ ∈ {0 ; 2 ; -1 ; 3 ; -3 ; 5} }$
    $\text{Vậy $n$ ∈ {0 ; 2 ; -1 ; 3 ; -3 ; 5} }$
    $Gấu trắng hơi non :)$

  2. n + 3 \vdots n – 1
    => ( n – 1 ) + 4 \vdots n – 1
    => 4 \vdots n – 1                             Vì n – 1 \vdots n – 1
    => n – 1 ∈ Ư(4) = {-4 ; -2 ; -1 ; 1 ; 2 ; 4}
    => n ∈ {-3 ; -1 ; 0 ; 2 ; 3 ; 5}
    Vậy n ∈ {-3 ; -1 ; 0 ; 2 ; 3 ; 5}
    #dtkc

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222-9+11+12:2*14+14 = ? ( )