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

Toán Lớp 8: |3x+2|+|2x+5|+|x+1|=10x |x-3|+|x+2|=7 Giúp mình 2 cậu này Cảm ơn

Toán Lớp 8: |3x+2|+|2x+5|+|x+1|=10x
|x-3|+|x+2|=7
Giúp mình 2 cậu này
Cảm ơn

Comments ( 2 )

  1. | 3x + 2| + |2x + 5| + |x + 1| = 10x
    => |3x + 2 + 2x + 5 + x + 1| = 10x
    => | 6x + 8| = 10x
    => \(\left[ \begin{array}{l}6x + 8 = 10x \\6x + 8 = -10x\end{array} \right.\) 
    => \(\left[ \begin{array}{l}6x – 10x =-8\\6x + 10x = -8\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}-4x=-8\\16x=-8\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}x=2\\x=-1/2\end{array} \right.\) 
    Vậy x ∈ { 2 ; -1/2 }
    | x – 3| + |x + 2| = 7
    => |x – 3 + x + 2|| = 7
    => |2x – 1| = 7
    =>\(\left[ \begin{array}{l}2x – 1=7\\2x – 1=-7\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}2x=8\\2=-6\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}x=4\\x=-3\end{array} \right.\) 
    Vậy x ∈ { 4 ; -3 }

  2. Giải đáp + Lời giải và giải thích chi tiết:
    | 3 x + 2 | + | 2 x + 5 | + | x + 1 | = 10 x
    <=> | 3 x + 2 + 2 x + 5 + x + 1 | = 10 x
    <=> | 6 x + 8 | = 10 x
    => $\left[\begin{matrix} 6 x + 8 = 10x\\ 6 x + 8 = -10x\end{matrix}\right.$ 
    <=> $\left[\begin{matrix} 6 x − 10 x = − 8\\ 6 x + 10 x = − 8\end{matrix}\right.$ 
    <=> $\left[\begin{matrix} − 4 x = − 8\\−  16 x = − 8\end{matrix}\right.$ 
    <=> $\left[\begin{matrix} x = 2\\x = \dfrac{-1}{2}\end{matrix}\right.$ 
    Vậy x ∈ { 2 ;-1/2 }
    | x − 3 | + | x + 2 | = 7
    <=> | x − 3 + x + 2 |  = 7
    <=> | 2 x − 1 | = 7
    => $\left[\begin{matrix} 2 x – 1 = 7\\2 x – 1 = -7\end{matrix}\right.$ 
    <=> $\left[\begin{matrix} 2 x  = 8\\2 x  = -6\end{matrix}\right.$ 
    <=> $\left[\begin{matrix} x = 4\\x =- 3\end{matrix}\right.$ 
    Vậy x ∈ { 4 ; − 3 }  
     

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

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