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

Toán Lớp 6: Tìm x : 86:[2*(2x-1)²-7]+(-4)²=2*(-3)²

Toán Lớp 6: Tìm x :
86:[2*(2x-1)²-7]+(-4)²=2*(-3)²

Comments ( 2 )

  1. 86÷[2(2x-1)²-7]-(4^2)=2.3²
    ⇒86÷[2(2x-1)²-7]+16=2.9
    ⇒86÷[2(2x-1)²-7]+16=18
    ⇒2(2x-1)²-7=16+18
    ⇒2(2x-1)²-7=86:2
    ⇒(2x-1)²=43+7
    ⇒(2x-1)²=50
    ⇒2x-1=50:2
    ⇒2x=25
    khd
     

  2. 86 : [2 . ( 2x -1)² – 7] + (-4)² = 2. (-3)²
    86 : [2 . ( 2x -1)² – 7] + 16 = 2 . 9
    86 : [2 . ( 2x -1)² – 7] + 16 = 18
    86 : [2 . ( 2x -1)² – 7] = 18 – 16
    86 : [2 . ( 2x -1)² – 7] = 2
     2 . ( 2x -1)² – 7 = 86 : 2
    2.(2x-1)² – 7 = 43
    2.(2x-1)² = 43 + 7
    2.(2x-1)² = 50
    (2x-1)² = 50 : 2
    (2x-1)² = 25
    (2x-1)² = 5²
    ⇒\(\left[ \begin{array}{l}2x-1 = 5\\2x-1 = -5\end{array} \right.\) 
    ⇒ \(\left[ \begin{array}{l}2x = 5 + 1\\2x = -5 + 1\end{array} \right.\) 
    ⇒\(\left[ \begin{array}{l}2x = 6\\2x = -4\end{array} \right.\) 
    ⇒ \(\left[ \begin{array}{l}x = 6:2\\2x = -4 : 2 \end{array} \right.\) 
    ⇒ \(\left[ \begin{array}{l}x=3\\x=-2\end{array} \right.\) 
    Vậy \(\left[ \begin{array}{l}x=3\\x=-2\end{array} \right.\) 

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

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