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A mediocre professor at a top-notch university making mediocre contributions to this top-notch community


May
14
comment Intuitive understanding of why the sum of nth roots of unity is $0$
@Jason: No, you won't get 1. For $x_1+x_4$ you'll get something like $.62$. But for $x_2+x_3$ you'll get about $-1.62$ which gives the $-1$ needed to cancel out the $1$ and obtain 0. Unfortunately, except for the $n=3$ example I gave, you don't get unit vectors along the way. I'll expand my answer for odd $n > 3$ later when I get time.
May
14
suggested suggested edit on Intuitive understanding of why the sum of nth roots of unity is $0$
May
13
answered Intuitive understanding of why the sum of nth roots of unity is $0$
May
12
comment Help to understand material implication
@joriki: Thanks, I modified my answer (slightly) to perhaps help in this respect.
May
12
revised Help to understand material implication
Minor clarification
May
12
answered Help to understand material implication
May
12
comment Edge of factoring technology?
@noonand: No problem, I appreciate the comment. :)
May
11
comment Edge of factoring technology?
Blah, sorry. I had "Schorr" originally (probably confused with Claus Schnorr, another cryptographer) and I "fixed" the spelling from "Schorr" to "Schor". Thanks to J.M.
May
11
answered Edge of factoring technology?
May
10
answered Find a number $b$ such that $a\cdot b\equiv 1\mod m$
May
9
answered Your favourite maths puzzles
May
9
comment Your favourite maths puzzles
I think this problem is a bit too well-known. en.wikipedia.org/wiki/Fair_coin#Fair_results_from_a_biased_coin
May
8
awarded  Enlightened
May
8
awarded  Nice Answer
May
8
comment Where did the word “logarithm” come from?
@Qiaochu: Note that I was requiring that the word be accepted as "elevated" to lowercase usage in order to sufficiently divorce it from its origin as a proper noun. Both "algorithm" and (often) "abelian" enjoy this status.
May
8
accepted Need a result of Euler that is simple enough for a child to understand
May
8
revised Where did the word “logarithm” come from?
added historical note
May
8
answered Where did the word “logarithm” come from?
May
7
answered Can this number theory MCQ be solved in 4 minutes?
May
7
comment Factorize $x^3-3x+2$
@cardano: since Jim didn't answer, I will: often you can notice small roots just from examination. For example, any polynomial with no constant term will have 0 as a root. If the sum of the coefficients sum to zero (as they do in your question) then 1 is a root. It's usually worth trying -1 as well. Most "real" polynomials won't have nice roots like this, but contrived homework problems and textbook problems will.