Good old Limits

Calculus Level 3

lim n 1 2 ( 2 n n ) 1 n = ? \displaystyle\large \lim_{n\to \infty} \frac{1}{2}\binom{2n}{n}^{\frac{1}{n}} = \, ?

Notation: ( M N ) = M ! N ! ( M N ) ! \dbinom MN = \dfrac {M!}{N! (M-N)!} denotes the binomial coefficient .

0 1 2 4

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1 solution

And why is that 2?

Peter van der Linden - 3 years, 2 months ago

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the limit will be 4 Since and half of it will be 2.

Naren Bhandari - 3 years, 2 months ago

I added the 1/2 just so that people would do that mistake at the end lol.

Arghyadeep Chatterjee - 3 years, 2 months ago

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Still why is 2 l o g ( 2 ) = 2 2log(2) = 2 ?

Peter van der Linden - 3 years, 2 months ago

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@Peter van der Linden 2log2 is not 2 . If you see that I said the limit equals e^L . where L=(after evaluating) 2log2. So the value equals 4 and then after dividing by 2 it becomes 2.

Arghyadeep Chatterjee - 3 years, 2 months ago

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@Arghyadeep Chatterjee Still don't get it... Log isn't the same as ln, so e^(2log2) is still not 4.

Peter van der Linden - 3 years, 2 months ago

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@Peter van der Linden Ok sorry my bad . Actually everyone are used take log as ln if no information about the base is mentioned . It is not a good thing to do in algebra but I think it is safe to do in calculus. Anyways I should have clarified that in my solution. It is actually a common practise in India to take log as ln .

Arghyadeep Chatterjee - 3 years, 2 months ago

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@Arghyadeep Chatterjee Aah then it's a translation problem! And I thought math was such a universal language. In Europe it's common to read base 10 if there's nothing mentioned as base.

Peter van der Linden - 3 years, 2 months ago

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@Peter van der Linden But anyways you should have figured it out that here log was to the base e when I raised the limit to the power of e.

Arghyadeep Chatterjee - 3 years, 2 months ago

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@Arghyadeep Chatterjee Nope I just got confused... And couldn't manage to figure it out anymore.

Peter van der Linden - 3 years, 2 months ago

@Arghyadeep Chatterjee Yeah it's matter of common and natural log.

Naren Bhandari - 3 years, 2 months ago

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