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

Toán Lớp 9: Tìm x:√4x^2+9+12x -2=0 Chú ý dấu căn từ 4x^2 đến 12x

Toán Lớp 9: Tìm x:√4x^2+9+12x -2=0 Chú ý dấu căn từ 4x^2 đến 12x

Comments ( 2 )

  1. y10000
    a )
    $\sqrt{4x²+9x+12x}$ – 2 = 0
    <=>\sqrt{4x²+12x+9}= 2
    <=> \sqrt{(2x+3)²}=2
    <=>|2x + 3|=2
    <=> \(\left[ \begin{array}{l}2x+3=2\\2x+3=-2\end{array} \right.\)
    <=> \(\left[ \begin{array}{l}x=\frac{-1}{2}\\x=\frac{-5}{2}\end{array} \right.\)
    $\text{Vậy x =…}$
     

  2. Em tham khảo:
         $\sqrt{4x^2+12x+9}-2=0$
    ⇔ $\sqrt{(2x+3)^2}-2=0$
    ⇔$| 2x+3|-2=0$
    ⇔$|2x+3| =2$
    ⇔\(\left[ \begin{array}{l}2x+3=2\\2x+3=-2\end{array} \right.\) 
    ⇔\(\left[ \begin{array}{l}x=-\dfrac{1}{2}\\x=-\dfrac{5}{2}\end{array} \right.\) 
    Học tốt
     

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