#Summarize the sum???

61 messages · Page 1 of 1 (latest)

deft helmBOT
dull solstice
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is the answer 2021/2023?

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@paper bramble

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nvm

paper bramble
dull solstice
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w8 i got it

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almost

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gimmi 5 mins

paper bramble
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how did u find it?

dull solstice
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u express 3 as n+2, like a general term

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u feel me?

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we basically use summation, taking the numerator as n+2 denominator as (n+2)! + (n+1)! + n!

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taking n from 1 to 2018

paper bramble
paper bramble
dull solstice
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try and tell me if u still didnt get it

paper bramble
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like this

dull solstice
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yes

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w8 no

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its n!(n+2) in the denominator

paper bramble
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I'm wrong ik ........

paper bramble
dull solstice
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yess

paper bramble
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but how to continue summarization?

dull solstice
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do uk telescopic series

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like in summations

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ill give u an example gimmi a min

paper bramble
dull solstice
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yes now think for a while how can u convert it

paper bramble
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oke

dull solstice
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got it?

paper bramble
dull solstice
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can u tell what is the basic requirement for telescopic

paper bramble
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serial limits??

dull solstice
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umm, i mean like a (-) in the numerator lmao

paper bramble
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mmm?

dull solstice
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okay ill give the solution

dull solstice
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now we multiply and divide with (n+1) in Nr and Dr

paper bramble
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yea

dull solstice
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then we again add and subtract 1 in Nr

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we get two terms

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n+2/(n+2)! - 1/ (n+2)!

dull solstice
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and then u get 1/(n+1)! - 1/(n+2)!

paper bramble
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oke thanks

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😊

dull solstice
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Hala madrid

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lol

brave plover
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I get $\frac{1}{2}-\frac{1}{2020!}$

dire tartanBOT
dark slate
dark slate
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Also ended up with this cool infinite series from adapting the problem.

brave plover
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I got the same result, but as
\begin{align*} &\frac{2}{0!+1!+2!}+\frac{3}{1!+2!+3!}+\frac{4}{2!+3!+4!}+... \ &=\sum_{k=1}^{\infty}\frac{k+1}{(k-1)!+k!+(k+1)!} \ &=\lim_{n\to\infty}{\sum_{k=1}^n\frac{k+1}{(k-1)!+k!+(k+1)!}} \ &=\lim_{n\to\infty}{\sum_{k=1}^n\frac{k}{(k+1)!}} \ &=\lim_{n\to\infty}{\sum_{k=1}^n\left(\frac{1}{k!}-\frac{1}{(k+1)!}\right)} \ &=\lim_{n\to\infty}\left(1-\frac{1}{(n+1)!}\right) \&=1 \end{align*}

dire tartanBOT
dark slate
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cool

paper bramble