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

Toán Lớp 6: 1. (2x -4).(3 – x) = 0 2. x – [42 + (-28)] = -8 3. |x-5|=|-7| Giúp em với ạ

Toán Lớp 6: 1. (2x -4).(3 – x) = 0
2. x – [42 + (-28)] = -8
3. |x-5|=|-7|
Giúp em với ạ

Comments ( 2 )

  1. Trả lời:
    1,(2x-4).(3-x)=0
    =>$\left[\begin{matrix} 2x-4=0\\ 3-x=0\end{matrix}\right.$
    =>$\left[\begin{matrix} 2x=4\\ x=3\end{matrix}\right.$
    =>$\left[\begin{matrix} x=2\\ x=3\end{matrix}\right.$
    $\text{Vậy}$ x in {2;3}
    2,x-[42+(-28)]=-8
    =>x-14=-8
    =>x=-8+14
    =>x=6
    $\text{Vậy}$ x=6
    3,|x-5|=|-7|
    =>|x-5|=7
    =>$\left[\begin{matrix} x-5=7\\ x-5=-7\end{matrix}\right.$
    =>$\left[\begin{matrix} x=12\\ x=-2\end{matrix}\right.$
    $\text{Vậy}$ x in {12;-2}

  2. 1. 
    (2x -4)(3-x)=0
    ⇒ \(\left[ \begin{array}{l}2x-4=0\\3-x=0\end{array} \right.\) 
    ⇒ \(\left[ \begin{array}{l}x=2\\x=3\end{array} \right.\) 
    Vậy …
    2.
    x – [42 + (-28)] = -8
    ⇒ x – 14 = -8
    ⇒ x= 6
    Vậy …
    3.
    |x-5|=|-7|
    ⇒ |x-5|=7
    ⇒ \(\left[ \begin{array}{l}x-5=7\\x-5=-7\end{array} \right.\) 
    ⇒ \(\left[ \begin{array}{l}x=12\\x=-2\end{array} \right.\) 
    Vậy ..
     

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

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