P=1/1.2.3+1/2.3.+1/3.4.5+…+1/2017.2018.2019

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1. `Thiếu đề : 1/(2*3)`

   `Sửa : 1/(2*3*4)`

   `P = 1/(1*2*3) + 1/(2*3*4) + 1/(3*4*5) + … + 1/(2017*2018*2019)`

   `2P = 2/(1*2*3) + 2/(2*3*4) + 2/(3*4*5) + … + 2/(2017*2018*2019)`

   `2P = 1/(1*2) – 1/(2*3) + 1/(2*3) – 1/(3*4) + …. + 1/(2017*2018)-1/(2018*2019)`

   `2P = 1/2 – 1/(2018*2019)`

   `2P = 2037170/(2018*2019)`

   `P = (2037170/(2018*2019))/2`

   `P = 1018585/(2018*2019)`

   `#KAITO#`

    

    

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