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  • Show that the infinite multiplication (1+1/1)(1+1/2)(1+1/3)... does not converge.
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[-] siriusmart@lemmy.world 1 points 5 months ago* (last edited 5 months ago)

Hint:

spoilere

Solution:

spoilerzkfcfbzr solved it

i put everything into ln because i was scared of multiplication

https://gmtex.siri.sh/fs/1/School/Extra/Maths/Qotd%20solutions/2024-05-16_telescoping-multiplication.html

[-] zkfcfbzr@lemmy.world 1 points 5 months ago* (last edited 5 months ago)

solutionThe terms can be rewritten as:

(2/1) * (3/2) * (4/3) * ... * ((n+1)/n) * ...

Each numerator will cancel with the next denominator. In total everything cancels, so the answer is the empty product, 1.

...Wait...

Uhm, ignore that. Rather, consider the products we get when multiplying. We get: 2/1. 6/2. 24/6. Etc. That is, we have:

Π (n = 1 to k) (n+1)/n = (k+1)! / k! = (k+1)k!/k! = k+1

k+1 clearly goes to infinity as k → ∞, so our product diverges to infinity.

this post was submitted on 16 May 2024
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