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Paragraph: If r ^ th term of a series can be writuen as a _ t = f ( r )- f ( r -1) , then S_a= _ r=1 ^n a_s=f(n)-f(0) and S_n= _ n S_n , then Question: Value of _ r=1 ^ (4 r-1) 5^r r^2+r is

Options

  1. A5
  2. B-5
  3. C10
  4. Dnone of these

Correct answer

C. 10

Step-by-step solution

a _ r = 5^ r +1 r +1 - 5^r r aligned & S_n=f(n)-f(0)= 5^ n+1 n+1 -5 & S_n aligned

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