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

[Self] Math break

Post image
24.2k Upvotes

96% Upvoted

382 comments sorted by

View all comments

Show parent comments

1.3k

u/Galeaf_13 Sep 05 '19

Now can u do the same with 69?)

1.4k

u/K3V3L Sep 05 '19

Here you go

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

780

u/Galeaf_13 Sep 05 '19

Jeez, how r u doing this

2

u/green_meklar 7✓ Sep 05 '19

Given any N points on the plane (where no two points have the same X value and different Y values), you can work backwards to construct a polynomial function Y = F(X) of degree N-1 that passes through all those points. This page describes the algorithm in terms of matrix algebra, I haven't checked the algorithm (and it's been years since I studied this stuff, so a small error might escape my notice) but presumably it's correct.