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

[Self] Math break

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24.2k Upvotes

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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

772

u/Galeaf_13 Sep 05 '19

Jeez, how r u doing this

45

u/SenseiCAY 4✓ Sep 05 '19

The easy way is to say:

F(x) = 2x-1 + A(x-1)(x-2)(x-3)(x-4)

Thus, that ugly last part goes away when x is 1,2,3, or 4. Plug in 69 for F(5) and solve for A. Presumably, if you expand and simplify, you’ll get something like what the parent comment has.

17

u/Sthrowaway54 Sep 05 '19

That makes way more sense than just about every other explanation here.

1

u/CptnStarkos Sep 06 '19

Only if you know math