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

Toán Lớp 9: $\sqrt[ ]{x^2-1} – 2\sqrt[]{x+1} = 0$

Tháng Bảy 9, 2022 Toán học 1 Comment 0 views

Toán Lớp 9: $\sqrt[ ]{x^2-1} – 2\sqrt[]{x+1} = 0$

Comments ( 1 )

  1. quynhmaithu
    quynhmaithu
    9 Tháng Bảy, 2022 at 2:29 sáng
    Reply
    #LC
    \sqrt(x^2-1) – 2\sqrt(x+1)=0 ĐKXĐ: \(\left[ \begin{array}{l}x\geq1\\x\leq-1\end{array} \right.\) 
    ⇔ \sqrt((x-1)(x+1)) – 2\sqrt(x+1)=0
    ⇔ \sqrt(x-1).\sqrt(x+1) – 2\sqrt(x+1)=0
    ⇔ \sqrt(x+1).(\sqrt(x-1)-2) =0
    ⇔ \(\left[ \begin{array}{l}\sqrt{x+1}=0\\\sqrt{x-1}=2\end{array} \right.\) 
    ⇔ \(\left[ \begin{array}{l}x+1=0\\x-1=4\end{array} \right.\) 
    ⇔ \(\left[ \begin{array}{l}x=-1(tm)\\x=5(tm)\end{array} \right.\) 
    Vậy, x ∈ {-1;5}

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

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