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

Toán Lớp 7: Tìm x biết : a) / 3x – 2 / = 4 b) / 5x – 3 / = / 7 – x / c) / 2x – 1 / = / 1 – x /

Toán Lớp 7: Tìm x biết :
a) / 3x – 2 / = 4
b) / 5x – 3 / = / 7 – x /
c) / 2x – 1 / = / 1 – x /

Comments ( 2 )

  1. Giải đáp+Lời giải và giải thích chi tiết:
    a)|3x – 2 |= 4 
    →\(\left[ \begin{array}{l}3x-2=4\\3x-2=-4\end{array} \right.\) 
    →\(\left[ \begin{array}{l}x=2\\x=-\dfrac{2}{3}\end{array} \right.\) 
    Vậy x={2/3;2}
    b)|5x – 3| = |7 – x |
    →\(\left[ \begin{array}{l}5x – 3 = 7 – x \\5x – 3 = -7 – x|\end{array} \right.\) 
    →\(\left[ \begin{array}{l}5x+x=10\\4x-3=-7\end{array} \right.\) 
    →\(\left[ \begin{array}{l}x=\dfrac{5}{3}\\x=-1\end{array} \right.\) 
    Vậy x={5/3;-1}
    c)|2x – 1| = |1 – x|
    →\(\left[ \begin{array}{l}2x – 1 = 1 – x\\2x – 1 = -1 – x\end{array} \right.\)
    →\(\left[ \begin{array}{l}2x+x=2\\2x-x=0\end{array} \right.\)
    →\(\left[ \begin{array}{l}x=\dfrac{2}{3}\\x=0\end{array} \right.\)
    Vậy x={2/3;0}

  2. text{Giải đáp + Lời giải và giải thích chi tiết}
    a)
    |3x-2|=4
    =>\(\left[ \begin{array}{l}3x-2=4\\3x-2=-4\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}3x=6\\3x=-2\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}x=2\\x=-2/3\end{array} \right.\) 
    Vậy x=2 hoặc x=-2/3
    b)
    |5x-3|=|7-x|
    =>\(\left[ \begin{array}{l}5x-3=7-x\\5x-3=x-7\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}6x=10\\4x=-4\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}x=5/3\\x=-1\end{array} \right.\) 
    Vậy x=5/3 hoặc x=-1
    c)
    |2x-1|=|1-x|
    =>\(\left[ \begin{array}{l}2x-1=1-x\\2x-1=x-1\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}3x=2\\x=0\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}x=2/3\\x=0\end{array} \right.\) 
    Vậy x=2/3 hoặc x=0
     

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