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If the sum of the first n terms of a series is n(2 n+1) , then what is the n th term?

Options

  1. A4 n-1
  2. B4 n
  3. C4 n+1
  4. D4 n+3

Correct answer

A. 4 n-1

Step-by-step solution

aligned & Here, S_n=n(2 n+1) S_ n-1 =(n-1)(2 n-1) & n^ th term =T_n=S_n-S_ n-1 & T_n=n(2 n+1)-(n-1)(2 n-1)=4 n-1 aligned

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