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

Toán Lớp 8: tìm x biết 3x ( 3x -5 ) – 2 ( 3x – 5 ) = 0

Toán Lớp 8: tìm x biết
3x ( 3x -5 ) – 2 ( 3x – 5 ) = 0

Comments ( 2 )

  1. \text{*Ta có: 3x.(3x-5)-2.(3x-5)=0}
    ⇒\text{(3x-5).(3x-2)=0}
    ⇒\(\left[ \begin{array}{l}3x-5=0\\3x-2=0\end{array} \right.\) 
    ⇒\(\left[ \begin{array}{l}3x=5\\3x=2\end{array} \right.\) 
    ⇒\(\left[ \begin{array}{l}x=\dfrac{5}{3}\\x=\dfrac{2}{3}\end{array} \right.\) 
    $\text{-Áp dụng:}$
    $\text{+Phương pháp đặt nhân tử chung}$
    $\text{+Công thức :(A+B).(C+D)=0}$
    ⇒\(\left[ \begin{array}{l}A+B=0\\C+D=0\end{array} \right.\) 
    _____________________________________
    $\text{#mct}$
     

  2. 3x(3x – 5) – 2(3x – 5) = 0
    (3x – 2)(3x – 5) = 0
    => 3x – 2 = 0 hoặc 3x – 5 = 0
    => 3x = 2 hoặc 3x = 5
    => x = 2/3 hoặc x = 5/3
    Vậy x in {2/3; 5/3}
     

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