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

Toán Lớp 6: 3n ∈ B(n – 1) Hãy tìm SỐ NGUYÊN N

Toán Lớp 6: 3n ∈ B(n – 1)
Hãy tìm SỐ NGUYÊN N

Comments ( 1 )

  1. $\text{ Vì 3n ∈ B(n – 1)  }$
    $\Rightarrow$ $\text{ 3n $\vdots$ n – 1   (1) }$
    $\text{ mà n – 1 $\vdots$ n – 1 }$
    $\Rightarrow$ $\text{ 3. ( n – 1 ) $\vdots$ n – 1 }$
    $\Rightarrow$ $\text{ 3n – 3 $\vdots$ n – 1       (2) }$
    $\text{ Từ (1) và (2) }$
    $\Rightarrow$ $\text{ 3n – ( 3n – 3 ) $\vdots$ n – 1 }$
    $\Rightarrow$ $\text{ 3 $\vdots$ n – 1 }$
    $\Rightarrow$ $\text{ n – 1 $\in$ Ư(3) = { $\pm$1 ; $\pm$3 } }$
    $\Rightarrow$ $\text{ n $\in$ { 0 ; 2 ; -2 ; 4 } }$
          $\text{ Vậy n $\in$ { 0 ; 2 ; -2 ; 4 } }$
     

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