#mathematical induction

45 messages · Page 1 of 1 (latest)

tawny sedge
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How do I get an expression to verify by induction?

coarse hamletBOT
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timid remnant
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what's going on here?

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this claim, if true, should be easy to get

tawny sedge
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But how can I rewrite sum from 1 to n+1 as sum from 1 to n + something

timid remnant
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$$ \sum _{k=1}^{n+1} \frac{1}{k+n} \geqslant \frac{7}{12} + \frac{1}{2n+1} $$

tender vergeBOT
timid remnant
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does this look right?

tawny sedge
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Can you explain how you get 1/(2n+1) ?

timid remnant
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put k=n+1, what do you get

tawny sedge
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Makes sense

tawny sedge
timid remnant
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what do you mean solve it?

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this inequality is already enough to prove induction step

tawny sedge
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I see it makes sense but my teacher gave this tip so I was trying to get this

timid remnant
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i don't see why subtraction is even necessary here

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I get that you have to use induction per the exercise instruction, but actually you dont even need it

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when you calculated base case

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the proof is already done

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from there you only ever add positive numbers on top

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if you want to formulate it by induction then it is enough to write this

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$$\sum _{k=1}^{n+1} \frac{1}{k+n} \geqslant \frac{7}{12} + \frac{1}{2n+1} > \frac{7}{12} $$

tender vergeBOT
timid remnant
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the claim is true for n+1 and you're done

tawny sedge
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I bet My teacher would like me to say that on the exam he is always saying to solve it the simplest way and if I remember correctly he already showed a look alike exercise where we just prove the 1st term for a fixed RHS

tawny sedge
timid remnant
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neither do I

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not in this context at least

autumn fjord
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?

tawny sedge
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How do I relate a(n+1) with a(n)

willow spade
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what i mean is that $a^2_n-n=a_{n-1}$

tender vergeBOT
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;( | 追放された興奮

willow spade
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because $a^2_n=n+\sqrt{(n-1)+\sqrt{(n-2)+...\sqrt{2+\sqrt{1}}}$

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and $a^2_n-n=\sqrt{(n-1)+\sqrt{(n-2)+...\sqrt{2+\sqrt{1}}}$

tender vergeBOT
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;( | 追放された興奮
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long otterBOT
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@tawny sedge

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swift sluice
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+close