Given the sum of the first n terms of an, Sn = 2 ^ n + K, find the value of K Given the sum of the first n terms of an, Sn = 2 ^ n + K, find the value of K

That's the problem
Use the special value method
S1=2+k
S2=4+k
S3=8+k
The solution is A1 = 2 + ka2 = 2A3 = 4
So because a is an equal ratio sequence, k = - 1

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