Lt n→∞ Lt x→0 1/(1tan2x+2tan2x+....Ntan2x)cot2x
We had a similar problem
http://www.targetiit.com/iit-jee-forum/posts/find-the-limit-10114.html
But I'm not sure about the answer...Plz someone give a complete explanation with answer :)
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2 Answers
kartik sondhi
·2009-08-13 09:39:24
as Lt x→0 by keeping11tan2x+2tan2x1tan3x..∞=y then Take log on both sides
log 1y= cot2xlog(tan2x+2tan2x1tan3x..∞)
then Take cot2x as 1tan2x
Now Diffrentiate on both sides As L'Hospital rule
and use the tan Expansion formula
then You will get the answer
Devil
·2009-08-13 09:43:16
Well, I think limit is 1.We will probably have lnk=cot2xln1, meaning k=1...