#Help Wolfie

119 messages · Page 1 of 1 (latest)

grim cliff
rocky nimbusBOT
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south nova
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So I assume Wolfie’e method was

  • Prove limit = e
  • Show Taylor Polynomial evaluates to e
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Maybe use pascal’s triangle to get an infinity term polynomial?

grim cliff
grim cliff
south nova
grim cliff
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okay okay thanks

still kraken
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What definition of e did Wolfie use?

still lynx
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yeah binomial expansion on the left

still lynx
still lynx
still kraken
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Yep i think, n!/(n^k) =(n-k)! ?n →∞

prisma pulsarBOT
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(xy)²=(yz)²=(xz)²=xyyzxz=-1

still lynx
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idk if you can swap lim and sum tho

still kraken
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You can

grim arch
still kraken
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Not sure but yeah

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@grim arch any reasoning why?

still lynx
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$= \sum_{r=0}^{\infty}\lim_{n\to\infty} \frac{n!}{(n-r)!r!} \left( \frac{1}{n^r} \right)$

prisma pulsarBOT
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(xy)²=(yz)²=(xz)²=xyyzxz=-1

grim cliff
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what

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are you binomial theoreming

still lynx
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yes

grim cliff
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i was looking for a faster method than mine ngl

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but yh it should work

still lynx
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$= \lim_{n\to\infty} (1/1! + \frac{n(n-1)}{2!n²} + \frac{n(n-1)(n-2)}{3!n³}+….)$

prisma pulsarBOT
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(xy)²=(yz)²=(xz)²=xyyzxz=-1

still lynx
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so looking at highest power coefficient

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$= 1/1! + \frac{1}{2!} + \frac{1}{3!}+…$

prisma pulsarBOT
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(xy)²=(yz)²=(xz)²=xyyzxz=-1

still lynx
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i think that proofed it

grim cliff
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this is just harder 💀

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but yh it works

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so i will credit u for that

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thanks @still lynx

exotic fractalBOT
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@grim cliff has given 1 rep to @still lynx

still lynx
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np

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actually not my idea i found part of it in math stackexchange

grim cliff
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imma let this thread be

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cuz i want a slicker solution if possible so imma go advertise my thread brb

cosmic light
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Need solution?

grim cliff
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yh

cosmic light
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This is quite standard so we can help Wolfie by repeating what we know.
First, we have $(1+1/n)^n=\sum_0^n {n\choose k} (1/n)^k=\sum_0^n {{[n]_k}\over {n^k}}\cdot {1\over {k!}}\le \sum_0^n {1\over {k!}}$ hence $\limsup (1+{1\over n})^n \le a$ where $a$ is RHS.
For the other direction, fix $s\ge 1$ and for $n\ge s$ we have $(1+1/n)^n=\sum_0^n {{[n]_k}\over {n^k}}\cdot {1\over {k!}}\ge \sum_0^s {{[n]_k}\over {n^k}}\cdot {1\over {k!}}$. The RHS here converges to $\sum_0^s {1\over {k!}}$ hence $\liminf (1+1/n)^n \ge \sum_0^s {1\over {k!}}$. This is true for all $s$ hence $\liminf (1+1/n)^n\ge a$.

prisma pulsarBOT
cosmic light
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Bye,enjoy

grim cliff
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um

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that notation is cursed

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what is sum 0 to n

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????

cosmic light
# grim cliff that notation is cursed

Expansion of $(1+\frac{1}{n})^n$ is[ 1 + {n\choose 1}\frac{1}{n} + {n\choose 2}(\frac{1}{n})^2 + ... + {n\choose n}(\frac{1}{n})^n ]A generic term of this series is[{n\choose k}(\frac{1}{n})^k]Expanding this we get[\frac{n!}{k!(n-k)!}(\frac{1}{n})^k]Simplifying it,[\frac{(n-k+1)(n-k+2)(n-k+3)....n}{k!}*(\frac{1}{n})^k]Seeing that the numerator is a polynomial of $\frac{1}{n}$ with degree k, we can simplify it further into[\frac{(1-\frac{k+1}{n})(1-\frac{k+2}{n})(1-\frac{k+3}{n})....1}{k!}]We can call the numerator as $P(\frac{1}{n})$
Expanding it we get $\frac{1}{k!} + \frac{1}{k!}*P(\frac{1}{n})$

We know that n is tending to infinity so $P(\frac{1}{n})$ tending to 0.
Therefore the generic term is $\frac{1}{k!}$

Since there are n terms, and starting from 0. The limit of the sum is[\sum_{k=0}^{\infty}\frac{1}{k!} ]

prisma pulsarBOT
still lynx
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literally what i did

grim arch
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Umm what was (n k) again?

grim cliff
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The coefficients of the terms in the binomial theorem are in the form $\binom{n}{k}; \binom{n}{k} = \frac{n!}{(n-k)!k!}$

prisma pulsarBOT
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wolfqz

still lynx
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n chooses k

grim cliff
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pascal tringle numbers

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ah yes pascal tringle

still lynx
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3d pascal triangle 😍

grim arch
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Thanks @grim cliff

exotic fractalBOT
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@wheat badge has given 1 rep to @grim cliff

south nova
cosmic light
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Few remarks. - $P$ depends on $k$ so the notation should be $P_k$.

  • the $k$-th term converges to $1/k!$ but, in general, that doesn't mean convergence of the sum since the number of terms tends to infinity. Here it's not a problem since ${{[n]_k}\over {n^k k!}}$ (with value 0 if $n>k$) is majorised by $1/k!$ and $\sum_0^\infty 1/k!$ is finite. Hence we can apply Lebesgue.
prisma pulsarBOT
iron mantle
iron mantle
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You need to sit down and actually know what you know, such discrepancies make people not trust what you're saying

cosmic light
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If you believe I am a high schooler based on my profile picture, then you are mistaken; that picture is of my sister

iron mantle
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No, I just think you're lying about your knowledge given the inconsistency you bring.

still kraken
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Just say you are an engineer 😄

cosmic light
grim cliff
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yoy

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stop fighting in this thread

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and start giving me better solutions

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🥰

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cuz the e method is better than binom

south nova
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Infinite term binomial >>>>

unique otter
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i've recently written a post on my blog for a generalized version of this. the most technical part is a math olympiad-type inequality

prisma pulsarBOT
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vin100

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vin100

unique otter
prisma pulsarBOT
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vin100

unique otter
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here i assumed knowledge on ratio/root test

heavy fossil
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@unique otter

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is this supposed to overlap?

grim cliff
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@heavy fossil

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provide good solution

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that isnt complicatied

heavy fossil
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tfyneed

grim cliff
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cuz all the solutions i got rn, mine is easier and better

heavy fossil
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context

grim cliff
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bro check pinned messages

heavy fossil
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okay what about it

grim cliff
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do the problem!!

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nah no way

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prove it

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idiot

heavy fossil
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dog what would I get

grim cliff
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nomination

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respect

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love

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affection

heavy fossil
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okay

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@grim cliff actually no yours is the shortest

grim cliff
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oh

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yay

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!!!!!!!!!!!!!!!!!!!

cosmic light
grim cliff
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convert both to e

unique otter
heavy fossil
grim cliff
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alright guys good one

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i got cpffey confirmation my method is best

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so im closing the thread

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+close