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  Discussion about math, puzzles, games and fun.   Useful symbols: √ ∞ ≠ ≤ ≥ ≈ ⇒ ∈ Δ θ ∴ ∑ ∫ π -

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Topic review (newest first)

Agnishom
2013-03-27 23:16:20

How dos it work?

anonimnystefy
2013-03-27 23:13:54

Yes it is.

Agnishom
2013-03-27 23:10:07

Is it a gf?

anonimnystefy
2013-03-27 22:54:43

Hm, try entering this into Maxima:

Code:

f(x):=ratexpand(product(1+x^i,i,1,10));
sum(coeff(f(x),x^i),i,12,55);
Agnishom
2013-03-27 22:44:52

Oh! Got it!
And if it wasn't half then how would you do the problem?

anonimnystefy
2013-03-27 22:07:50

No. If it is >=12, the complement's element sum is less than 55-12=43.

Agnishom
2013-03-27 22:03:22

Suppose it is some other number, say 12
Now for all sets whose sum is >=12 their compliments sum is <12
Therefore there are as many sets which sum more than or equal to 12 as the sets which sum less than 12
So....????

anonimnystefy
2013-03-27 22:00:22

Why is that?

Agnishom
2013-03-27 15:35:14

On second thoughts.... I doubt it sad

anonimnystefy
2013-03-27 04:10:21

You are welcome! smile

Agnishom
2013-03-27 03:54:51

I mean I understood TY smile

anonimnystefy
2013-03-27 03:39:15

What is it?

Agnishom
2013-03-27 02:58:06

Hmm...

anonimnystefy
2013-03-27 01:13:18

It is half because if a set's sum of elements is >=28, then the sum of elements of its complement is <28. That means that there are as many subsets of the given set which have the element sum >=28 as there are with the element sum <28.

bobbym
2013-03-27 01:02:37

Yes, they let you use Mathematica there.

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