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

Toán Lớp 6: 5x+19 chia hết cho 2x+1 GẤPPPPPP

Toán Lớp 6: 5x+19 chia hết cho 2x+1
GẤPPPPPP

Comments ( 2 )

  1. 5x+19 $\vdots$ 2x+1
    ⇒$\left \{ {{5x+19 \vdots 2x+1} \atop {10x+38 \vdots 10x+5}} \right.$ 
    ⇒$\left \{ {{10x+38 \vdots 10x+5} \atop {10x+5 \vdots10x+5}} \right.$ 
    ⇒(10x+38)-(10x+5) $\vdots$ 10x+5
    ⇒10x+38-10x-5 $\vdots$ 10x+5
    ⇒33  $\vdots$ 10x+5
    ⇒10x+5∈Ư(33)
    ⇒10x+5∈{±1;±3;±11;±33}
    ⇒x∈{0;-1;-2;1;-6;5;-17;16}
    Vậy x∈{0;-1;-2;1;-6;5;-17;16}

  2. 5x+19\vdots 2x+1
    =>2(5x+19)\vdots 2x+1
    =>10x+38\vdots 2x+1
    =>10x+5+33\vdots 2x+1
    =>5(2x+1)+33\vdots 2x+1
    Vì 5(2x+1)\vdots 2x+1
    5(2x+1)+33\vdots 2x+1
    =>33\vdots 2x+1
    =>2x+1∈Ư(33)={+-1;+-3;+-11;+-33}
    =>2x∈{0;-2;-4;2;-12;10;-34;32}
    =>x∈{0;-1;-2;1;-6;5;-17;16}
    Vậy 5x+19\vdots 2x+1=>x∈{0;-1;-2;1;-6;5;-17;16}
    – Tính chất : a+-b\vdots m
    $\begin{cases}a\vdots m⇒b\vdots m\\ b\vdots m⇒a\vdots m\end{cases}$

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