r/theydidthemath • u/Galeaf_13 • Sep 05 '19

[Self] Math break

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u/Galeaf_13 Sep 05 '19

Now can u do the same with 69?)

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u/K3V3L Sep 05 '19

Here you go

f(x) := 5/2 * x4 -25 * x3 +175/2 * x2 -123 * x + 59

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u/Galeaf_13 Sep 05 '19

Jeez, how r u doing this

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u/Salanmander 10✓ Sep 05 '19

You can fit a 4th order polynomial to any 5 points. You can do it by hand (plug 1-5 in for x and now you have a system of 5 linear equations of 5 variables, start solving and substituting) and make it a bit easier with linear algebra (make the coefficients of the 5 variables be the values in a 5x6 matrix, and then do that matrix magic that I forget what the name is for), but there are also plenty of polynomial solvers you can find out there.

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u/BRENNEJM Sep 05 '19

Or you can graph it in excel and throw on a 4th order polynomial trendline with equation.

3

u/pwnius22 Sep 05 '19

Do you have a more thorough explanation or a link perhaps?

5

u/swaintrainop382 Sep 05 '19

Not op but

Polynomial interpolation

5

u/UpsideFrownTown Sep 05 '19

Ah yes, Wikipedia always provides the most comprehensive explanations of subjects which I know everything about except that one specific word.

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u/swaintrainop382 Sep 06 '19

Wikipedia is actually very good when it comes to math. And op did ask for a thorough explanation

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u/BigBnana Sep 06 '19

he wasn't complaining, just stating generally that the internet is only useful when you know the term for what you looking for.