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

Toán Lớp 8: $9x^{2}$ – 25 – x( 3x + 5 ) = 0

Toán Lớp 8: $9x^{2}$ – 25 – x( 3x + 5 ) = 0

Comments ( 2 )

  1. Giải đáp+Lời giải và giải thích chi tiết:
     ~Bạn Tham Khảo~
    9x²-25-x(3x+5)=0
    ⇒(3x-5)(3x+5)-x(3x+5)=0
    ⇒(3x+5)(3x-5-x)=0
    ⇒(3x+5)(2x-5)=0
    ⇒\(\left[ \begin{array}{l}3x+5=0\\2x-5=0\end{array} \right.\) 
    ⇒\(\left[ \begin{array}{l}3x=-5\\2x=5\end{array} \right.\) 
    ⇒\(\left[ \begin{array}{l}x=-5/3\\x=5/2\end{array} \right.\) 
    vậy x∈{$\frac{-5}{3}$ ;$\frac{5}{2}$ }

  2. Giải đáp + giải thích:
    9x²-25-x(3x+5)=0
    ⇔ (3x – 5)(3x+5) – x( 3x + 5 ) = 0
    ⇔ (3x+5)(3x-5-x)=0
    ⇔ (3x+5)(2x-5)=0
    TH1: 3x+5 =0 ⇔x=-5/3
    TH2: 2x – 5 =0⇔x=5/2
    Vậy x∈{-5/3; 5/2}

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