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

Toán Lớp 6: tìm n thuộc N sao cho (10-2n) chia hết cho (n-2)

Toán Lớp 6: tìm n thuộc N sao cho (10-2n) chia hết cho (n-2)

Comments ( 2 )

  1. 10 – 2n
    = -2n +10
    = (-2n +4) – 4 +10
    = -2( n-2) + 6
    \text{Vì}   -2(n-2)   \vdots (n-2)
    => 6   \vdots (n-2)
    => n-2 ∈ Ư(6) ={-6;-3;-2;-1;1;2;3;6}
    => n ∈ {-4;-1;0;1;3;4;5;8}
    \text{mà n ∈ N}
    => n ∈ {0;1;3;4;5;8}
    \text{Vậy}  n ∈{0;1;2;3;4;5;8}   \text{thì}    (10-2n)  \vdots (n-2)

  2. (10-2n)⋮(n-2)
    ⇒6-2.(n-2)⋮(n-2)
    Mà 2.(n-2)⋮(n-2)
    ⇒6⋮(n-2)
    ⇒(n-2)∈Ư(6)={1;2;3;6}
    ⇔n∈{3;4;5;8}
    Vậy n∈{3;4;5;8}
    Xin hay nhất#21kamehameha

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