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

Toán Lớp 7: x-15/1999 + x-1998/8 + x-4/670=6 ,tìm x đi

Toán Lớp 7: x-15/1999 + x-1998/8 + x-4/670=6 ,tìm x đi

Comments ( 2 )

  1. Giải đáp:
    (x-15)/1999 + (x-1998)/8 + (x-4)/670=6
    <=> (x-15)/1999 + (x-1998)/8 + (x-4)/670 – 6= 0
    <=> (x-15)/1999 + (x-1998)/8 + (x-4)/670 + ( -1 – 2 – 3)=0
    <=> ((x-15)/1999 – 1) + (( x- 1998)/8 -2) + ((x-4)/670 – 3) = 0
    <=> (x-2014)/1999 + (x-2014)/8 + (x-2014)/670 = 0
    <=> (x-2014) ( 1/1999 + 1/8 + 1/670 )= 0
    <=> x – 2014 = 0
    <=> x= 2014
    Vậy S= { 2014}

  2. Lời giải và giải thích chi tiết:
     $\dfrac{x-15}{1999}+\dfrac{x-1998}{8}+\dfrac{x-4}{670}=6$
    $\Rightarrow (\dfrac{x-15}{1999}-1)+(\dfrac{x-1998}{8}-2)+(\dfrac{x-4}{670}-3)=0$
    $\Rightarrow \dfrac{x-2014}{1999}+\dfrac{x-2014}{8}+\dfrac{x-2014}{670}=0$
    $\Rightarrow (x-2014)(\dfrac1{1999}+\dfrac18+\dfrac1{670})=0$
    $\Rightarrow x-2014=0$
    $\Rightarrow x=2014$

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