`A = (-1)/3+1/3 ²-1/3 ³ + 1/3` mũ 4 -…+1/3 mũ 50 – 1/3 mũ 51

1 bình luận về “`A = (-1)/3+1/3 ²-1/3 ³ + 1/3` mũ 4 -…+1/3 mũ 50 – 1/3 mũ 51”

1. A = (-1)/3 + 1/3^2 – 1/3^3 + 1/3^4 – … + 1/(3^(50)) + 1/(3^(51))

   3A = (-1) + 1/3 – 1/3^2 + 1/3^3 – … + 1/(3^(49)) – 1/(3^(51))

   3A + A = [ (-1) + 1/3 – 1/3^2 + 1/3^3 – … + 1/(3^(49)) – 1/(3^(51)) ] + [ (-1)/3 + 1/3^2 – 1/3^3 + 1/3^4 – … + 1/(3^(50)) + 1/(3^(51)) ]

   4A = (-1) + 1/(3^(51))

   A = ( (-1) + 1/(3^(51))) )/4

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