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What is the sum of first eight terms of the series 1- 1 2 + 1 4 - 1 8 + ?

Options

  1. A89 128
  2. B57 384
  3. C85 128
  4. DNone of the above

Correct answer

C. 85 128

Step-by-step solution

1- 1 2 + 1 4 - 1 8 + Sum of first ' n ' terms of G.P. S_n=1 (1- (- 1 2 )^8 ) 1- (- 1 2 ) = 1- 1 256 1+ 1 2 = 255 256 3 2 = 85 128 .

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