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

Toán Lớp 8: (x-1)-(2x-1)=x+4 3x(x-2)+4(x-2)=0

Toán Lớp 8: (x-1)-(2x-1)=x+4
3x(x-2)+4(x-2)=0

Comments ( 2 )

  1. (x-1)-(2x-1)=x+4
    ⇔x-1-2x+1=x+4
    ⇔-2x-4=0
    ⇔-2(x+2)=0
    ⇔x+2=0
    ⇔x=-2
    3x(x-2)+4(x-2)=0
    ⇔(x-2)(3x+4)=0
    ⇔x-2=0 hoặc 3x+4=0
    ⇔x=2 hoặc x=-4/3
     

  2. Lời giải:
    1)
    (x-1)-(2x-1)=x+4
    ⇔x-1-2x+1-x-4=0
    ⇔(x-2x-x)+(-1+1-4)=0
    ⇔-2x-4=0
    ⇔-2x=4
    ⇔x=-2
    Vậy x=-2
    2)
    3x(x-2)+4(x-2)=0
    ⇔(x-2)(3x+4)=0
    $\left[\begin{matrix}x-2=0\\3x+4=0\end{matrix}\right.$
    $\left[\begin{matrix}x=2\\x=\dfrac{-4}{3}\end{matrix}\right.$
    Vậy x∈{2;-4/3}

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