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Determine the sums of the following geometric series.

1. \(1 + 5 + 25 + 125 + ... + t_6 \)
   
   
   
2. \(S_8 = 16 + 4 + 1 + \frac{1}{4} + ... \)
   
   
   
3. \(t_n = 32, t_1 = \frac{1}{16}, r = -2 \)