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

Toán Lớp 9: Giải phương trình √ 4x^2+12x+9 =5

Toán Lớp 9: Giải phương trình √ 4x^2+12x+9 =5

Comments ( 2 )

  1. $\text{$\sqrt{4x²+12x+9}$=5}$
    $\text{⇔$\sqrt{(2x+3)²}$=5}$
    $\text{⇔l 2x+3l=5}$
    $\text{⇔\(\left[ \begin{array}{l}2x+3=5\\2x+3=-5\end{array} \right.\)}$
    $\text{⇔\(\left[ \begin{array}{l}x=1\\x=-4\end{array} \right.\)}$
    $\text{Vậy S={1;-4}}$
     

  2. $\sqrt{4x² + 12x + 9}$ = 5
    ⇔ $\sqrt{(2x+3)²}$ = 5
    ⇔ 2x + 3 = ± 5
    ⇔ x = 1 hoặc x = -4
     

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