Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °
You are not logged in.
Post a reply
Topic review (newest first)
It is long and arduous. There is no discernible pattern which to me is a sure sign of the "wrong method!"
And why is the method ugly?
Principle of Inclusion and Exclusion
What is PIE?
Yes, I am partly through a very ugly method to do a slightly harder one then you proposed. Unfortunately earlier today I came across a method that uses PIE but I do not follow it. So this may not be any mystery to anyone but me.
I was not aware it was an open field of research. Did you say you were writing a paper on it? How many different formulae have they found?
What ideas do you have to get it?
It is also not quite as simple as that either. What if you needed x^7's coefficient and the power was 1 000 000 000. Wolfram can not get that.
I understand, but this sort of thing will probably come up in either STEP I, II or III. It's usually the first question and they want you to do it 'systematically' -- which takes 15-25 minutes. But if I use a shortcut, it could take 2 minutes! In an exam where time is of the essence, those extra minutes could be a whole grade.
That is a different problem then the one we were working on back around #9500.
That is because that one is too short. To be on the safe side it should be at least:
Suppose we want the co-efficient of x^7 in:
Which one does it not work for? Do you have an example?
Yeah, that's what I wrote at the top of the page -- but it doesn't always seem to work...
I think I have it, I do not know how we got confused back then . Let's try again.
with k is the power, n is x^n. This should work fine.