tính s = 1/9+1/81+1/729+1/6561+1/59049

1 bình luận về “tính s = 1/9+1/81+1/729+1/6561+1/59049”

1. S = 1/9+1/81+1/729+1/6561+1/59049

   S = 1/9 + 1/9^2 + 1/9^3+9^4+9^5

   9S = 9(1/9+1/9^2+1/9^3+1/9^4+1/9^5)

   9S = 1+1/9+1/9^2+1/9^3+1/9^4

   9S-S=(1+1/9+1/9^2+1/9^3+1/9^4)-(1/9+1/9^2+1/9^3+1/9^4+1/9^5)

   8S = 1 – 1/9^5

   S = (1-1/9^5)/8

   Trả lời