#function math

30 messages · Page 1 of 1 (latest)

ripe crypt
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Given y=f(x), how many nature numbers n so that y=|f(x)+n| has 5 extremiums

swift tundraBOT
ripe crypt
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I got f(x) = x^4 - 2x^2 -3

ripe crypt
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That’s funn

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Can you text me how you did that?

heavy stump
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Presumably by using f'(x) = a(x-1)(x+1)x expanding, integrating, and then using two points f(1) = -4 and f(0) = -3 to fix the constant a, and the constant of integration.

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@ripe crypt

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@ripe crypt so when you abs, you fold the negative numbers into positive ones, right? This creates extrema at zeroes. So this function has 3 extrema normally, so as long as it crosses the x axis twice it will have two more extrema.

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So this is equivalent to asking for how many natural numbers does this equation have only 2 zeroes.

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If n = 0, this is true (is 0 a natural number for you?), and this remains true up until 3 where you have 3 zeroes, but it doesn't cross, so n=3 works.

ripe crypt
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0 Is the trivial solution

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I think

heavy stump
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I'm not sure what you mean by that

ripe crypt
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Oh ok

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Like homogeneous linear equations? Maybe that doesn’t apply

heavy stump
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Beyond that the function has no zeroes.

heavy stump
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It's solvable with direct integration

ripe crypt
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Yeah

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That’s cool

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So absolute value creates new solutions?

heavy stump
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Absolute value can create new extrema

ripe crypt
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Nice

heavy stump
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It can turn an odd counted zero into a minima.

ripe crypt
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WOW

ripe crypt
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Tysm ❤️

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.close

swift tundraBOT
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Solved

Post marked as solved by @charred stirrup.

Use .unsolved if this was a mistake.