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

Toán Lớp 6: Giải giúp em với ạ!Em cảm ơn trước,sẽ vote 5 sao ạ. (2x-1)²=49

Toán Lớp 6: Giải giúp em với ạ!Em cảm ơn trước,sẽ vote 5 sao ạ.
(2x-1)²=49

Comments ( 2 )

  1. (2x – 1)^{2} = 49
    $\Rightarrow$ (2x – 1)^{2} = (+- 7)^{2}
    $\Rightarrow$ $\left[\begin{matrix} 2x-1=7\\ 2x-1=-7\end{matrix}\right.$
    $\Rightarrow$ $\left[\begin{matrix} 2x=7+1\\ 2x=-7+1\end{matrix}\right.$
    $\Rightarrow$ $\left[\begin{matrix} 2x=8\\ 2x=-6\end{matrix}\right.$
    $\Rightarrow$ $\left[\begin{matrix} x=8:2\\ x=-6:2\end{matrix}\right.$
    $\Rightarrow$ $\left[\begin{matrix} x=4\\ x=-3\end{matrix}\right.$
    $\text{Vậy}$ x \in {4 ; -3}
     

  2. (2x-1)^2=49
    (2x-1)^2=7^2;-7^2
    =>Th1:2x-1=7
    =>2x=7+1
    =>2x=8
    =>x=8:2
    =>x=4
    ———-
    =>Th2:2x-1=-77
    =>2x=-7+1
    =>2x=-6
    =>x=-6:2
    =>x=-3
    Vậy x=-3;4

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

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