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Jul 21, 2019 at 20:26 vote accept EtherealMist
Jul 21, 2019 at 13:11 history edited Sil
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Jul 21, 2019 at 13:01 answer added Sil timeline score: 1
Jul 20, 2019 at 23:49 comment added EtherealMist @Sil I see. Unfortunately we don't deal with infinite sums in this course so it would have to be by induction. I just can't see it, though. Thanks for the help.
Jul 20, 2019 at 22:33 comment added Sil Not by induction (induction is generally bad when you want to compare inequality of form $f(n)<c$ with a constant $c$ (there is no reason why if $f(n)=0.999999$ should imply that $f(n+1)<1$ as well). This is usually resolved by proving stronger statement instead, something like $f(n)<c-\frac{1}{n}$, which in this case might be tricky to find. Without induction, there is quite an easy proof though, you can prove that the infinite sum $\sum_{i=0}^{\infty} \frac{F_i}{2^{2+i}}=1$, and since individual terms are non-negative, the statement follows.
Jul 20, 2019 at 22:27 comment added EtherealMist @Sil I don't know. The question was just given that way. Any tips or hints? I'm really having trouble figuring it out.
Jul 20, 2019 at 22:25 comment added Sil Why $n+2$? This is true even with $\sum_{i=0}^{n} \frac{F_i}{2^{2+i}} < 1$
Jul 20, 2019 at 20:01 comment added EtherealMist Does anyone have any hints to solve this? Some additional context: this is a first year intro to proofs course.
Jul 20, 2019 at 19:47 comment added EtherealMist It is $2^{2+i}$
Jul 20, 2019 at 9:10 answer added Witold timeline score: 1
Jul 20, 2019 at 7:04 comment added DanielWainfleet @GerryMyerson/ I assumed that $2^2+i$ was a typo and edited it.
Jul 20, 2019 at 7:03 comment added DanielWainfleet It is more common to define $F_0=0$ and $F_1=F_2=1.$
Jul 20, 2019 at 6:52 history edited DanielWainfleet CC BY-SA 4.0
typo. punctuation.
Jul 20, 2019 at 4:38 comment added Gerry Myerson You have $2^{2+i}$ in one place, $2^2+i$ in another. They are different. Which (if either) do you want?
Jul 20, 2019 at 2:47 history reopened mechanodroid
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Jul 19, 2019 at 23:20 review Reopen votes
Jul 20, 2019 at 2:47
Jul 19, 2019 at 23:07 comment added EtherealMist @MarkFischler I edited the question to add more details. Could you clarify your comment?
Jul 19, 2019 at 23:02 history edited EtherealMist CC BY-SA 4.0
Added more information/context.
Jul 19, 2019 at 22:53 comment added Mark Fischler Evidently he means the second of those definitions; otherwise $\frac12$ is an upper bound.
Jul 19, 2019 at 22:43 history closed Martin R
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Jul 19, 2019 at 22:36 history asked EtherealMist CC BY-SA 4.0