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

Toán Lớp 6: tìm số nguyên x (x+4 )chia hết cho (2x+1)

Toán Lớp 6: tìm số nguyên x
(x+4 )chia hết cho (2x+1)

Comments ( 1 )

  1. (x + 4) vdots (2x + 1)
    ⇒ 2(x + 4) vdots (2x + 1)
     ⇒ 2x + 2.4 vdots 2x + 1
    ⇒ 2x + 8 vdots 2x + 1
    ⇒ 2x + 1 + 7 vdots 2x + 1
    ⇒ (2x + 1) + 7 vdots 2x + 1
    ⇒ 2x + 1 ∈ $Ư(7)$
    Ta có :
    $Ư(7)$ = {±1 ; ±7}
    ⇒ 2x + 1 ∈ {±1 ; ±7}
    ⇒ 2x ∈ {0 ; -2 ; 6 ; -8}
    ⇒ x ∈ {0 ; -1 ; 3 ; -4}
    Vậy x = {0 ; -1 ; 3 ; -4}

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