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Given sum of the first n terms of an A.P. is 2 n+3 n^2 . Another A.P. is formed with the same first term and double of the common difference, the sum of n terms of the new A.P. is :

Options

  1. An+4 n^2
  2. B6 n^2-n
  3. Cn^2+4 n
  4. D3 n+2 n^2

Correct answer

B. 6 n^2-n

Step-by-step solution

Given S _n=2 n+3 n^2 Now, first term =2+3=5 second term =2(2)+3(4)=16 third term =2(3)+3(9)=33 Now, sum given in option (b) only has the same first term and difference between 2 nd and 1 st term is double also.

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