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math104-s21:s:johndufek [2021/05/07 06:13]
73.71.56.149
math104-s21:s:johndufek [2026/02/21 14:41] (current)
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 . A very helpful technique for proving the limit of some sequence where it is really hard to isolate n can be the following: \\ . A very helpful technique for proving the limit of some sequence where it is really hard to isolate n can be the following: \\
 //Example: say you want to prove the limit of $\frac{4n^3 + 3n}{n^3 - 6} => \frac{3n+24}{n^3 - 6} = 4 $ . It would be hard to isolate $n$ to find such an $N > 0$. \\ //Example: say you want to prove the limit of $\frac{4n^3 + 3n}{n^3 - 6} => \frac{3n+24}{n^3 - 6} = 4 $ . It would be hard to isolate $n$ to find such an $N > 0$. \\
-Hence bound the sequence by something easier i.e. $3n + 24 \leq 27n$. Thus $\frac{27n}{n^3 - 6} < \epsilon$. Building off this technique we know the denominator $n^3 - 6 \geq frac{n^3}{2}$ . Hence $frac{27n}{n^3 / 2} < \epsilon => \frac{54}{n^2} < \epsilon$ .Then from here you can easily find an $N > 0$ s.t. the limit definition holds. // \\+Hence bound the sequence by something easier i.e. $3n + 24 \leq 27n$. Thus $\frac{27n}{n^3 - 6} < \epsilon$. Building off this technique we know the denominator $n^3 - 6 \geq \frac{n^3}{2}$ . Hence $\frac{27n}{n^3 / 2} < \epsilon => \frac{54}{n^2} < \epsilon$ .Then from here you can easily find an $N > 0$ s.t. the limit definition holds. This technique is displayed in Ross page 40 - 41.// \\ 
 + 
 +//See Ross textbook chapter 9 for useful limit properties and theorems.//\\ 
 + 
 +**Sequences**\\ 
 + 
  
  
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 $(b)\ d(p,q)\ =\ d(q,p)$ \\ $(b)\ d(p,q)\ =\ d(q,p)$ \\
 $( c )\ d(p,q)\ \le \ d(p,r)\ +\ d(r,q),\ for\ any\ r\ \in \ X$ \\ $( c )\ d(p,q)\ \le \ d(p,r)\ +\ d(r,q),\ for\ any\ r\ \in \ X$ \\
-$d(x,y)\ =\ |x-y|\ (x,y\ \in \ R^k \ )$ \\+$d(x,y)\ =\ |x-y|\ (x,y\ \in \R^k \ )$ \\
  
 . A K-cell is convex and compact\\ . A K-cell is convex and compact\\
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 2)  2) 
 +
 +**Limits**\\
 +
 +1) How can we know/ differentiate certain approaches to particular limits of sequences that satisfy L'Hopital criteria and yield an answer but it is in fact the wrong answer?
  
math104-s21/s/johndufek.1620368011.txt.gz · Last modified: 2026/02/21 14:44 (external edit)