Limit of $frac{(n-1)^{2n-1-k}}{n^n (n-1-k)^{n-1-k}}$
I'm trying to calculate the limit of $$frac{(n-1)^{2n-1-k}}{n^n (n-1-k)^{n-1-k}}$$ as $n to infty$. I know (using Wolfram Alpha) that the limit should be equal to $e^{k-1}$. However I'm unable to manipulate the expression in the way that I could see the limit to be true.
limits
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I'm trying to calculate the limit of $$frac{(n-1)^{2n-1-k}}{n^n (n-1-k)^{n-1-k}}$$ as $n to infty$. I know (using Wolfram Alpha) that the limit should be equal to $e^{k-1}$. However I'm unable to manipulate the expression in the way that I could see the limit to be true.
limits
add a comment |
I'm trying to calculate the limit of $$frac{(n-1)^{2n-1-k}}{n^n (n-1-k)^{n-1-k}}$$ as $n to infty$. I know (using Wolfram Alpha) that the limit should be equal to $e^{k-1}$. However I'm unable to manipulate the expression in the way that I could see the limit to be true.
limits
I'm trying to calculate the limit of $$frac{(n-1)^{2n-1-k}}{n^n (n-1-k)^{n-1-k}}$$ as $n to infty$. I know (using Wolfram Alpha) that the limit should be equal to $e^{k-1}$. However I'm unable to manipulate the expression in the way that I could see the limit to be true.
limits
limits
edited Nov 27 at 12:23
Martin Sleziak
44.7k7115270
44.7k7115270
asked Oct 30 at 12:47
Kplusn
1199
1199
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2 Answers
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Just split it up appropriately. A possible way is as follows:
$$frac{(n-1)^{2n-1-k}}{n^n (n-1-k)^{n-1-k}} = frac{(n-1)^{2n}cdot (n-1-k)^{k+1}}{n^ncdot (n-1-k)^n cdot (n-1)^{k+1}} $$ $$ = underbrace{frac{(n-1-k)^{k+1}}{(n-1)^{k+1}}}_{stackrel{n to infty}{longrightarrow}1}cdot underbrace{frac{(n-1)^n}{n^n}}_{stackrel{n to infty}{longrightarrow}e^{-1}}cdot underbrace{frac{1}{frac{(n-1-k)^n}{(n-1)^n}}}_{stackrel{n to infty}{longrightarrow}frac{1}{e^{-k}} =e^{k}}$$
Great! I tried to do it in a similar way but seems that Im not that good of a splitter.
– Kplusn
Oct 30 at 13:08
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HINT
We have
$$dfrac{(n-1)^{2n-1-k}}{n^n (n-1-k)^{n-1-k}}=dfrac{(n-1)^n}{n^n }dfrac{(n-1)^{n-1-k}}{ (n-1-k)^{n-1-k}}=left( 1-frac1n right)^nfrac{1}{left( 1-frac k{n-1} right)^{n-1-k}}$$
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
Just split it up appropriately. A possible way is as follows:
$$frac{(n-1)^{2n-1-k}}{n^n (n-1-k)^{n-1-k}} = frac{(n-1)^{2n}cdot (n-1-k)^{k+1}}{n^ncdot (n-1-k)^n cdot (n-1)^{k+1}} $$ $$ = underbrace{frac{(n-1-k)^{k+1}}{(n-1)^{k+1}}}_{stackrel{n to infty}{longrightarrow}1}cdot underbrace{frac{(n-1)^n}{n^n}}_{stackrel{n to infty}{longrightarrow}e^{-1}}cdot underbrace{frac{1}{frac{(n-1-k)^n}{(n-1)^n}}}_{stackrel{n to infty}{longrightarrow}frac{1}{e^{-k}} =e^{k}}$$
Great! I tried to do it in a similar way but seems that Im not that good of a splitter.
– Kplusn
Oct 30 at 13:08
add a comment |
Just split it up appropriately. A possible way is as follows:
$$frac{(n-1)^{2n-1-k}}{n^n (n-1-k)^{n-1-k}} = frac{(n-1)^{2n}cdot (n-1-k)^{k+1}}{n^ncdot (n-1-k)^n cdot (n-1)^{k+1}} $$ $$ = underbrace{frac{(n-1-k)^{k+1}}{(n-1)^{k+1}}}_{stackrel{n to infty}{longrightarrow}1}cdot underbrace{frac{(n-1)^n}{n^n}}_{stackrel{n to infty}{longrightarrow}e^{-1}}cdot underbrace{frac{1}{frac{(n-1-k)^n}{(n-1)^n}}}_{stackrel{n to infty}{longrightarrow}frac{1}{e^{-k}} =e^{k}}$$
Great! I tried to do it in a similar way but seems that Im not that good of a splitter.
– Kplusn
Oct 30 at 13:08
add a comment |
Just split it up appropriately. A possible way is as follows:
$$frac{(n-1)^{2n-1-k}}{n^n (n-1-k)^{n-1-k}} = frac{(n-1)^{2n}cdot (n-1-k)^{k+1}}{n^ncdot (n-1-k)^n cdot (n-1)^{k+1}} $$ $$ = underbrace{frac{(n-1-k)^{k+1}}{(n-1)^{k+1}}}_{stackrel{n to infty}{longrightarrow}1}cdot underbrace{frac{(n-1)^n}{n^n}}_{stackrel{n to infty}{longrightarrow}e^{-1}}cdot underbrace{frac{1}{frac{(n-1-k)^n}{(n-1)^n}}}_{stackrel{n to infty}{longrightarrow}frac{1}{e^{-k}} =e^{k}}$$
Just split it up appropriately. A possible way is as follows:
$$frac{(n-1)^{2n-1-k}}{n^n (n-1-k)^{n-1-k}} = frac{(n-1)^{2n}cdot (n-1-k)^{k+1}}{n^ncdot (n-1-k)^n cdot (n-1)^{k+1}} $$ $$ = underbrace{frac{(n-1-k)^{k+1}}{(n-1)^{k+1}}}_{stackrel{n to infty}{longrightarrow}1}cdot underbrace{frac{(n-1)^n}{n^n}}_{stackrel{n to infty}{longrightarrow}e^{-1}}cdot underbrace{frac{1}{frac{(n-1-k)^n}{(n-1)^n}}}_{stackrel{n to infty}{longrightarrow}frac{1}{e^{-k}} =e^{k}}$$
answered Oct 30 at 13:01
trancelocation
9,1051521
9,1051521
Great! I tried to do it in a similar way but seems that Im not that good of a splitter.
– Kplusn
Oct 30 at 13:08
add a comment |
Great! I tried to do it in a similar way but seems that Im not that good of a splitter.
– Kplusn
Oct 30 at 13:08
Great! I tried to do it in a similar way but seems that Im not that good of a splitter.
– Kplusn
Oct 30 at 13:08
Great! I tried to do it in a similar way but seems that Im not that good of a splitter.
– Kplusn
Oct 30 at 13:08
add a comment |
HINT
We have
$$dfrac{(n-1)^{2n-1-k}}{n^n (n-1-k)^{n-1-k}}=dfrac{(n-1)^n}{n^n }dfrac{(n-1)^{n-1-k}}{ (n-1-k)^{n-1-k}}=left( 1-frac1n right)^nfrac{1}{left( 1-frac k{n-1} right)^{n-1-k}}$$
add a comment |
HINT
We have
$$dfrac{(n-1)^{2n-1-k}}{n^n (n-1-k)^{n-1-k}}=dfrac{(n-1)^n}{n^n }dfrac{(n-1)^{n-1-k}}{ (n-1-k)^{n-1-k}}=left( 1-frac1n right)^nfrac{1}{left( 1-frac k{n-1} right)^{n-1-k}}$$
add a comment |
HINT
We have
$$dfrac{(n-1)^{2n-1-k}}{n^n (n-1-k)^{n-1-k}}=dfrac{(n-1)^n}{n^n }dfrac{(n-1)^{n-1-k}}{ (n-1-k)^{n-1-k}}=left( 1-frac1n right)^nfrac{1}{left( 1-frac k{n-1} right)^{n-1-k}}$$
HINT
We have
$$dfrac{(n-1)^{2n-1-k}}{n^n (n-1-k)^{n-1-k}}=dfrac{(n-1)^n}{n^n }dfrac{(n-1)^{n-1-k}}{ (n-1-k)^{n-1-k}}=left( 1-frac1n right)^nfrac{1}{left( 1-frac k{n-1} right)^{n-1-k}}$$
edited Oct 30 at 13:09
answered Oct 30 at 13:02
gimusi
1
1
add a comment |
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