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

Toán Lớp 8: 3x^2-5x-2=0 chứng minh giúp vs mn

Toán Lớp 8: 3x^2-5x-2=0 chứng minh giúp vs mn

Comments ( 2 )

  1. 3x^2-5x-2=0
    <=>3x^2+x-6x-2=0
    <=>x(3x+1)-2(3x+1)=0
    <=>(3x+1)(x-2)=0
    <=>$\left[\begin{matrix} 3x+1=0\\ x-2=0\end{matrix}\right.$
    <=>$\left[\begin{matrix} x=-\dfrac{1}{3}\\ x=2\end{matrix}\right.$
    Vậy S={-1/3; 2}

  2. 3x² – 5x – 2 = 0
    ⇔ 3x² – 6x + x – 2 = 0
    ⇔ 3x(x – 2) + (x – 2) = 0
    ⇔ (x – 2)(3x + 1) = 0
    ⇔ \(\left[ \begin{array}{l}x – 2 = 0\\3x + 1 = 0\end{array} \right.\) 
    ⇔ \(\left[ \begin{array}{l}x = 2\\x = -\dfrac{1}{3}\end{array} \right.\) 
    Vậy x ∈ {2; -$\dfrac{1}{3}$}
    Chúc bạn học tốt
     

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