tìm x biết x-1/2019 +x-2/2018+x-3/2017=3

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1. Đáp án:

   `(x-1)/2019+(x-2)/2018+(x-3)/2017=3`

   `<=>(x-1)/2019+(x-2)/2018+(x-3)/2017-3=0`

   `<=> ((x-1)/2019 -1)+((x-2)/2018 -1)+((x-3)/2017 -1)=0`

   `<=> (x-2020)/2019+(x-2020)/2018+(x-2020)/2017=0`

   `<=> (x-2020).(1/2019+1/2018+1/2017)=0`

   Mà `1/2019+1/2018+1/2017>0`

   `<=> x-2020=0`

   `<=> x=2020`

    

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