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

Toán Lớp 8: Giá trị x thỏa mãn:x(x-2)+x-2=0 là: A.x=1;x=2 B.x=2 C.x=-1;x=2. D.x=0;x=2

Toán Lớp 8: Giá trị x thỏa mãn:x(x-2)+x-2=0 là:
A.x=1;x=2 B.x=2
C.x=-1;x=2. D.x=0;x=2

Comments ( 2 )

  1. x(x-2)+x-2=0
    <=>x(x-2)+(x-2)=0
    <=>(x-2)(x+1)=0
    <=>\(\left[ \begin{array}{l}x-2=0\\x+1=0\end{array} \right.\) 
    <=>\(\left[ \begin{array}{l}x=2\\x=-1\end{array} \right.\) 
    Vậy x=2 hoặc x=-1
    ->C
     

  2. Answer
    x . (x – 2) + x – 2 = 0
    => x . (x – 2) + (x – 2) . 1 = 0
    => (x + 1) . (x – 2) = 0
    => $\left[\begin{matrix} x+1=0\\ x-2=0\end{matrix}\right.$
    => $\left[\begin{matrix} x =0 – 1\\ x =0 + 2\end{matrix}\right.$
    => $\left[\begin{matrix} x =- 1\\ x = 2\end{matrix}\right.$
    $\text{Vậy}$ x \in {-1 ; 2}
    => $\text{Chọn C}$

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

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