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

Toán Lớp 7: 8x-|4x+1|=x+2 KHÔNG SAO CHÉP MẠNG

Toán Lớp 7: 8x-|4x+1|=x+2
KHÔNG SAO CHÉP MẠNG

Comments ( 2 )

  1. 8x – |4x + 1| = x + 2
    |4x + 1| = 8x – (x + 2)
    |4x + 1| = 8x – x – 2
    |4x + 1| = 7x – 2
    ⇒ \(\left[ \begin{array}{l}4x+1=7x-2\\4x+1=2-7x\end{array} \right.\) 
    ⇒ \(\left[ \begin{array}{l}3x=3\\11x=1\end{array} \right.\) 
    ⇒ \(\left[ \begin{array}{l}x=1\\x=\dfrac{1}{11}\end{array} \right.\) 
    Vậy x = 1

  2. 8x-|4x+1|=x+2
    =>|4x+1|=8x-(x+2)
    =>|4x+1|=8x-x-2
    =>|4x+1|=7x-2(x>=2/7)
    =>[(4x+1=7x-2),(-4x-1=7x-2):}
    =>[(7x-4x=1+2),(7x+4x=-1+2):}
    =>[(3x=3),(11x=1):}
    =>$\left[\begin{matrix} x=1(tm) \\ x=\dfrac{1}{11}(ktm)\end{matrix}\right.$
    Vậy x=1

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

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