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Please solve the problem in the attachment ......... ANS is 1..........

Please solve the problem in the attachment ......... ANS is 1.......... 

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Grade:12th pass

1 Answers

Aditya Gupta
2081 Points
5 years ago
Write pi√(n^2+n) as npi√(1+1/n)
Now using binomial theorem for fractional indices, expand (1+1/n)^1/2 as 1+1/2n+O(1/n^2)
Multiply by npi and take cosine
cos(npi+pi/2+O(1/n)) = - sin(npi+O(1/n))
As n tends to infinity, O(1/n) becomes zero.
Also, sinnpi is always zero as long as n is an integer. So the limit is zero. so your answer 1 is clearly wrong so kindly recheck and revert back if you have any doubts.

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