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If the first n terms of a sequence and the formula Sn = (the nth power of 3) + B (B is a constant), is the sequence an equal ratio sequence?
An = SN-S (n-1) = (3 ^ n + b) - [3 ^ (n-1) + b] = 2 * 3 ^ (n-1) (n ≥ 2) an / a (n-1) = [2 * 3 ^ (n-1)] / [2 * 3 ^ (n-2)] = 3 is a constant, A1 = 2 * 3 ^ (1-1) = 2 and A1 = S1 = 3 + B. therefore, when 3 + B = 2, i.e. B = - 1, this sequence is an equal ratio sequence. When B ≠ - 1, A1 = 3 + B, an = 2 * 3 ^ (n-1) (n ≥ 2), this sequence starts from the second
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