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anonymous
 5 years ago
how can we prove that a(n) = n/n+1 converges by using the definition? I know how to find the limit, yet I can't seem to find a way to prove it using the definition
anonymous
 5 years ago
how can we prove that a(n) = n/n+1 converges by using the definition? I know how to find the limit, yet I can't seem to find a way to prove it using the definition

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anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0I might be able to help you. I would consider the following:\[\lim_{n>\infty}\frac{n}{n+1}=\lim_{n>\infty}\frac{1}{1+\frac{1}{n}}\]and from limit laws, \[\frac{1}{1+\lim_{n \rightarrow \infty} \frac{1}{n}}\]Now, for \[\lim_{n \rightarrow \infty}\frac{1}{n}\]choose \[\epsilon >0\] small. Let N be the first integer greater than \[\frac{1}{\epsilon}\]Then\[\forall n>N \rightarrow n>\frac{1}{\epsilon} \iff \forall n>N \rightarrow \epsilon >\frac{1}{n} \iff \frac{1}{n}< \epsilon\]Since n>0,\[0<\frac{1}{n}< \epsilon \iff 0<\frac{1}{n}  0 < \epsilon\] and so, by definition of the limit,\[\frac{1}{n} \rightarrow 0 \] as \[n \rightarrow \infty\]

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0So,\[\lim_{n>\infty}\frac{n}{1+n}=\lim_{n>\infty}\frac{1}{1+\frac{1}{n}}=\frac{1}{1+\lim_{n>\infty}\frac{1}{n}}=\frac{1}{1+0}=1\]

nowhereman
 5 years ago
Best ResponseYou've already chosen the best response.0You even do not need that limit law, if you already know the limit. Just calculate \[1\frac{n}{1+n} = \frac{1}{1+n}\] so need only find n for ε so that \[\frac 1 {1+n} < ε ⇔ n > \frac 1 ε  1\] Thus if you choose \[ n = \frac 1 ε \] everythings fine.
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