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The sum of the series 3-1+ 1 3 - 1 9 + . is equal to

Options

  1. A20 9
  2. B9 20
  3. C9 4
  4. D4 9

Correct answer

C. 9 4

Step-by-step solution

The series is 3 3^0 - 3 3^1 + 3 3^2 - 3 3^3 + This is a G.P. with first term a=3 and common ratio r=- 1 3 Sum S = 3 1- (- 1 3 ) = 3 3 3+1 = 9 4

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