a,2.(x-1)+3(x-2)=x-4 b,(x+2).(3-x)=0 c,x-{57-[42+(-23-x)]}=13-{47+[25-(32-x)]}

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1. Đáp án:

    

   Giải thích các bước giải:

   a/ $2(x-1)+3(x-2)=x-4$
   => $2x-2+3x-6-x+4=0$
   => $4x-4=0$
   => $x-1=0$
   => $x=1$
   b/ $(x+2)(3-x)=0$
   => \(\left[ \begin{array}{l}x+2=0\\3-x=0\end{array} \right.\)
   => \(\left[ \begin{array}{l}x=-2\\x=3\end{array} \right.\)
   c/ $x-{57-[42+(-23-x)]}=13-{47+[25-(32-x)]}$
   => $x-(57-[42+(-23-x)])=13-(47+[25-(32-x)])$
   => $x-(57-[42-23-x])=13-(47+[25-32+x)])$
   => $x-(57-42+23+x)=13-(47+25-32+x)$
   => $x-(38+x)=13-(40+x)$
   => $x-38-x=13-40-x$
   => $x=13-40+38=11$
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2. `a, 2.(x-1)+3(x-2)=x-4`

       `2x-2+3x-6-x=-4`

        `4x-8=-4`

        `4x=-4+8`

        `4x=4`

        `x=4:4`

        `x=1`

   `b, (x+2).(3-x)=0`

   `=> x+2=0`  hoặc `3-x=0`

         `x=0-2`           `x=3-0`

         `x=-2`              `x=3`

   `c, x-{57-[42+(-23-x)]}=13-{47+[25-(32-x)]}`

       `x-[57-(42-23-x)]=13-[47+(25-32+x)]`

      `x-[57-(19-x)]=13-(47+25-32+x)`

      `x-(57-19+x)=13-(40+x)`

      `x-(38+x)=13-40-x`

      `x-38-x=-27-x`

      `-38=-27-x`

      `-x-27=-38`

      `-x=(-38)+27`

      `-x=-11`

    `=> x=11`

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