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

Toán Lớp 6: bài 1:tìm số nguyên X ,biết a) 9.(x+28)=0 b) (27-x).(x+9) c) (-x).(x-43)=0

Toán Lớp 6: bài 1:tìm số nguyên X ,biết
a) 9.(x+28)=0
b) (27-x).(x+9)
c) (-x).(x-43)=0

Comments ( 2 )

  1. a/
    9(x+28) =0
    => x +28 =0
    => x = 0 -28
    => x = -28
    Vậy x = -28
    $\\$
    b/
    (27-x)(x+9) =0
    <=> \(\left[ \begin{array}{l}27 -x =0\\x+9 =0\end{array} \right.\) 
    <=> \(\left[ \begin{array}{l}x=27\\x=-9\end{array} \right.\) 
    Vậy x \in {27 ; -9}
    c/
    (-x)(x-43) =0
    <=> \(\left[ \begin{array}{l}-x =0\\x-43 =0\end{array} \right.\) 
    <=> \(\left[ \begin{array}{l}x=0\\x=43\end{array} \right.\) 
    Vậy x \in {0 ; 43}   

  2. Giải Pháp
    a.
    ${9⋅(x+28)=0 }$
    ${x+28=0}$
    ${x=−28}$
    b.
    ${(27-x).(x+9)}$
    $={27x+243−x 2 −9x}$
    $={18x+243−x 2}$
    c.
    ${ (-x).(x-43)=0}$
    ${}(−x)x−43(−x)=0$
    ${(−x)x+43x=0}$
    ${−x^ 2 +43x=0}$
    ${x(−x+43)=0}$
    ${x=0}$
    $x={43}$
     

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