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

Toán Lớp 6: Tìm x thuộc Z bt : a) x.(x+3)=0

Toán Lớp 6: Tìm x thuộc Z bt : a) x.(x+3)=0
b) (x-2).(5-x)=0
c) (x-1).(x^2+1)=0

Comments ( 2 )

  1. a.
    x . (x + 3) = 0
    => \(\left[ \begin{array}{l}x=0\\x + 3 = 0\end{array} \right.\) 
    => \(\left[ \begin{array}{l}x=0\\x=-3\end{array} \right.\) 
    Vậy x ∈ {0 ; -3}
    b.
    (x – 2) . (5 – x) = 0
    => \(\left[ \begin{array}{l}x – 2 = 0\\5 – x = 0\end{array} \right.\) 
    => \(\left[ \begin{array}{l}x=2\\x=5\end{array} \right.\) 
    Vậy x ∈ {2 ; 5}
    c.
    (x – 1) . (x^2 + 1) = 0
    => \(\left[ \begin{array}{l}x – 1 = 0\\x^2 + 1 = 0\end{array} \right.\) 
    => \(\left[ \begin{array}{l}x=1 (TM)\\x^2=-1 (KTM)\end{array} \right.\) 
    Vậy x = 1

  2. Giải đáp+Lời giải và giải thích chi tiết:
    a) x.(x+3)=0
    <=> \(\left[ \begin{array}{l}x=0\\x+3=0\end{array} \right.\) 
    <=> \(\left[ \begin{array}{l}x=0\\x=-3\end{array} \right.\) 
      Vậy x∈{0; -3}
    b) (x-2).(5-x)=0
    <=>\(\left[ \begin{array}{l}x-2=0\\5-x=0\end{array} \right.\) 
    <=>\(\left[ \begin{array}{l}x=2\\x=5\end{array} \right.\) 
       Vậy x∈{2; 5}
    c) (x-1).(x^2+1)=0
    <=> \(\left[ \begin{array}{l}x-1=0\\x^{2}+1=0\end{array} \right.\) 
    <=> \(\left[ \begin{array}{l}x=1\\x^{2}=-1(vô nghiệm)\end{array} \right.\) 
       Vậy x=1

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

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