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

Toán Lớp 8: (4x+2)+2(5x-2)^2-2(4x+1)(5x-2)=0.Tìm x ạ Giúp vs cần ngay

Toán Lớp 8: (4x+2)+2(5x-2)^2-2(4x+1)(5x-2)=0.Tìm x ạ
Giúp vs cần ngay

Comments ( 2 )

  1. (4x + 2) + 2(5x – 2)^2 – 2(4x + 1)(5x – 2) = 0
    (4x + 2) + 2(5x – 2)(5x – 2) – 2(4x + 1)(5x – 2) = 0
    2( 5x – 2 ) ( 5x + 1 )                            = 0
    ⇔$\left[\begin{matrix} 5x-2=0\\ 5x+1=0\end{matrix}\right.$
    ⇔$\left[\begin{matrix} 5x=2\\ 5x=-1\end{matrix}\right.$
    ⇔$\left[\begin{matrix} x=2/5\\ x=-1/5\end{matrix}\right.$
    (TM)

  2. (4x+2)+2(5x-2)² – 2(4x+1)(5x-2) = 0 
    2( 5x – 2 ) ( 4x + 2 + 5x – 2 – 4x + 1 ) = 0 
    2( 5x – 2 ) ( 5x + 1 )                            = 0
    ⇔ 2 = 0 ( vô lí ) 
    ⇔ 5x – 2 = 0 ⇒ x = $\frac{-2}{5}$ 
    ⇔ 5x + 1 = 0 ⇒ x = $\frac{1}{5}$ 
    Vậy S = { $\frac{-2}{5}$ ; $\frac{1}{5}$ } 

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