#Infinite series

38 messages · Page 1 of 1 (latest)

hidden timber
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Can anybody help me with this question

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Number 43

young herald
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did you try to use the ratio test?

young herald
hidden timber
# young herald ;

Don't believe I've learned that yet. The tests we've learned are nth term, geometric series, telescoping, p series, and integral test

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The problem should be solvable using just those

young herald
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ah okay, also looks like the ratio test doesn't even work lol

hidden timber
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I have a picture of the answer key, though I can't understand that either

young herald
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could you send me it?

hidden timber
young herald
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ah

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i assume you're aware the harmonic series diverges

hidden timber
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Yes

young herald
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what they did was rewrite the series such that each term of the series is greater than each corresponding term of the harmonic series

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well half of the harmonic series anyways but that diverges also

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does that make sense? my wording might be a little scuffed lol

hidden timber
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How exactly did they re write it? I guess that's what I'm confused about

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For example in line 2, why is the 1/2n factored out?

young herald
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they shifted everything over by one

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kind of like telescoping series?

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if you try to match each term from the numerator to the corresponding term on the denominator

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the second numerator term matches with the first denominator

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the third numerator with the second denominator

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etc

hidden timber
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What is the point of that?

young herald
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until you get to the nth denominator term, which has nothing to match with

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uhh

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you know telescoping series

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it's like

hidden timber
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Yeah ik what telescoping is

young herald
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so it's similar to the final step

hidden timber
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Where is stuff canceling though?

young herald
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ok can you watch my stream

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i'll draw it out

hidden timber
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Where is the stream?

young herald
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not sure if theres a vc channel

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can i just call you?