Monday, 23 January 2017

How to calculate limit of the sequence e(nfrac12)(n+1)100





Does the sequence e(n12)(n+1)100 converge? If yes what is the limit?




What I tried: Expanding
(n+1)100=1+100C1n+100C2n2+100C3n3++100C100n100


Multiplying each term by e(n12) and taking limits using L'Hospital Rule we get the limit of the sequence 0, but that is a lengthy and I think it is not a proper approach. [Actually applying L'Hospital rule twice to each term gives the preceding term(I checked it upto [n3e(n12)] and hence ultimately limit will be 0 because lim(e(n12))=0]
Can anyone please tell me whether this is a correct method to solve the problem and please suggest me a proper method if there is any. Thank you.



The answer is limit of the sequence is 0


Answer



Yes, the final limit is zero. Note that as n+

en(n+1)100=exp(n(1100ln(n+1)n)1)0


because, for example by using L'Hopital,
limn+ln(n+1)n=0.


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