Sn = 1 / 2 + 3 / 2 ^ 2 + 5 / 2 ^ 3 +... + (2n-1) / 2 ^ n sum My foundation is not good, please try to be more detailed,

Sn = 1 / 2 + 3 / 2 ^ 2 + 5 / 2 ^ 3 +... + (2n-1) / 2 ^ n (1) 2Sn = 2 (1 / 2 + 3 / 2 ^ 2 + 5 / 2 ^ 3 +... + (2n-1) / 2 ^ n) = 1 + 3 / 2 + 5 / 2 ^ 2 +... + (2n-1) / 2 ^ (n-1) (2) subtraction (subtraction with denominator) Sn = 2Sn Sn = 1 + 2 / 2 + 2 / 2 ^ 2 +... + 2 / 2 ^ (n-1) - (2n-1) / 2 ^ n = 2 (1 + 1

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