Search found 855 matches

by Buttons
Wed Mar 11, 2009 11:17 pm UTC
Forum: Mathematics
Topic: Favorite math jokes
Replies: 1452
Views: 457407

Re: Favorite math jokes

Root can mean to have sex with. I don't think we've fully explored the possibilities here. To wit: A mathematician and his wife are at a couples therapy session. The counselor, to break the ice, asks them to briefly describe their sexual histories, at which point the mathematician admits that he's ...
by Buttons
Wed Mar 11, 2009 5:16 pm UTC
Forum: Mathematics
Topic: Definitions & explanations in English/Actual uses for math
Replies: 19
Views: 1628

Re: Definitions & explanations in English/Actual uses for math

It is possible to be a very good mathematician, and it is possible to be a very good math teacher. The two are (mostly) independent. From my experience with the OSU math department of doom, I'd guess that they're negatively correlated. I don't know about that. Certainly the skills needed to be a go...
by Buttons
Wed Mar 11, 2009 5:10 pm UTC
Forum: Mathematics
Topic: Matrices
Replies: 26
Views: 2429

Re: Matrixes

The top-right entry is correct, but the others are not. Could you maybe show your calculations so I can see where you're going wrong?
by Buttons
Wed Mar 11, 2009 1:39 pm UTC
Forum: Mathematics
Topic: Definitions & explanations in English/Actual uses for math
Replies: 19
Views: 1628

Re: Definitions & explanations in English/Actual uses for math

Wildcard, I sort of agree with you at this point, but I still think you're focusing on the wrong thing. The "why" of mathematics (science!) has been drilled into students' heads for decades, but it rarely causes people to change their minds. I think the "how" is more important. T...
by Buttons
Mon Mar 09, 2009 11:18 pm UTC
Forum: Mathematics
Topic: combinations that confuse
Replies: 13
Views: 1378

Re: combinations that confuse

That's a cute little tool. I like that it lists the possibilities for you.
by Buttons
Mon Mar 09, 2009 11:15 pm UTC
Forum: Mathematics
Topic: Love note
Replies: 3
Views: 747

Re: Love note

<3 is a bit overplayed. (About four years ago, I wooed someone with a note containing a triangle of side lengths I, U and 2U.) You should pioneer the "ε>" love note instead.
by Buttons
Mon Mar 09, 2009 12:44 pm UTC
Forum: Mathematics
Topic: how do I solve these number sequences?
Replies: 19
Views: 3722

Re: how do I solve these number sequences?

I think auteur52 is correct here. We shouldn't assume that serious employers are conducting evaluations of job applicants via Scantron. Rather, these sorts of tests are often oral, and the emphasis is usually on explaining the thought process.
by Buttons
Sat Mar 07, 2009 7:48 pm UTC
Forum: Mathematics
Topic: Real life arguments solved with math
Replies: 12
Views: 1329

Re: Real life arguments solved with math

I'm not sure what you mean when you say that the points of Sierpinski's triangle are chosen at random. Can you explain this?
by Buttons
Sat Mar 07, 2009 4:53 pm UTC
Forum: Mathematics
Topic: dexa- rotation of mathematical proportion/equations
Replies: 7
Views: 1086

Re: dexa- rotation of mathematical proportion/equations

Yes, I believe I've seen this before. You might look into the research of Lilly, Otsuka, and Janssen and Cilag.
by Buttons
Wed Mar 04, 2009 12:23 am UTC
Forum: Mathematics
Topic: Favourite Erroneous "Proofs"
Replies: 194
Views: 40917

Re: Favourite Erroneous "Proofs"

DavCrav wrote:How about the diagonal fallacy?

Googling this yields startlingly few results. Would something like
one of my students wrote:{an : n in N} is regular, and {bn : n in N} is regular, and the regular languages are closed under concatenation, therefore {anbn : n in N} is regular.
qualify?
by Buttons
Tue Mar 03, 2009 10:36 pm UTC
Forum: Mathematics
Topic: combinations that confuse
Replies: 13
Views: 1378

Re: combinations that confuse

You can see a similar problem (albeit with a very different wording) tackled here.
by Buttons
Mon Mar 02, 2009 11:39 pm UTC
Forum: Mathematics
Topic: Sum of Corners
Replies: 11
Views: 1272

Re: Sum of Corners

Indeed, AHDag, there is no polyhedron, regular or otherwise, made only out of hexagons, nor is there one made solely out of any n-gon for n > 5.
by Buttons
Mon Mar 02, 2009 8:28 pm UTC
Forum: Mathematics
Topic: Sum of Corners
Replies: 11
Views: 1272

Re: Sum of Corners

I think what the OP is trying to calculate is the sum of the sum of the interior angles of all the polygons that make up the polyhedron. Oh, that's what he was trying to compute! Gotcha. Fortunately, this is easy. For a polyhedron with n vertices, the sum is 360n-720. To see why, read about angle d...
by Buttons
Mon Mar 02, 2009 4:55 pm UTC
Forum: Mathematics
Topic: Sum of Corners
Replies: 11
Views: 1272

Re: Sum of Corners

In any case, I don't think there's any way of making a polyhedron out of 27 hexagons, not even an irregular one. Indeed. Such a polyhedron would have 81 (= 27*6/2) edges and therefore 56 vertices. But 81*2/56 = 2.89, so the average degree of a vertex is less than 3, which is impossible. (And in gen...
by Buttons
Mon Mar 02, 2009 2:17 pm UTC
Forum: Mathematics
Topic: Sum of Corners
Replies: 11
Views: 1272

Re: Sum of Corners

Well, if you think of a polygon as a cycle of points \lbrace p_0,p_1,\dots,p_{n-1}\rbrace in the plane, then the angle at a "corner" i is just the angle between the vectors \overline{p_ip_{i-1}} and \overline{p_ip_{i+1}} , where the indices are taken modulo n. It's easy to see that for n=2...
by Buttons
Fri Feb 27, 2009 7:27 pm UTC
Forum: Mathematics
Topic: Favorite math jokes
Replies: 1452
Views: 457407

Re: Favorite math jokes

(I believe the joke was that 59 is LIX.)
by Buttons
Thu Feb 26, 2009 2:40 pm UTC
Forum: Mathematics
Topic: Limit comparison test
Replies: 20
Views: 1678

Re: Limit comparison test

Isn't it true that if the known function is in the denominator and convergent, and you get zero, then the unknown function is convergent too?
by Buttons
Thu Feb 26, 2009 1:59 pm UTC
Forum: Mathematics
Topic: Number of primes...
Replies: 8
Views: 1258

Re: Number of primes...

Of the first pk integers, k of them are prime, namely p1 through pk.
by Buttons
Thu Feb 26, 2009 4:50 am UTC
Forum: Mathematics
Topic: solve this triangle for x
Replies: 10
Views: 1630

Re: solve this triangle for x

Are the red segments supposed to have the same length? Alternately, are the two vertical-looking lines supposed to be parallel? If not, I don't believe there's enough information.
by Buttons
Thu Feb 26, 2009 12:52 am UTC
Forum: Mathematics
Topic: So that's why math is awesome.
Replies: 19
Views: 1905

Re: So that's why math is awesome.

Yeah, that was unreasonably harsh, Tac-Tics. (Also, since when are words like "omniscient" considered obscure?)
by Buttons
Wed Feb 25, 2009 11:07 pm UTC
Forum: Mathematics
Topic: Favorite math jokes
Replies: 1452
Views: 457407

Re: Favorite mathematics jokes

That filter is gonna be a problem. Did it just get implemented?

(Also, it's 69, haha, get it? Like the sex act!)

EDIT: You're kidding. There's a filter on the word f-i-l-t-e-r?
by Buttons
Wed Feb 25, 2009 10:52 pm UTC
Forum: Mathematics
Topic: Favorite math jokes
Replies: 1452
Views: 457407

Re: Favorite mathematics jokes

That's an interesting avatar for someone who hasn't done calculus.
by Buttons
Wed Feb 25, 2009 8:58 pm UTC
Forum: Mathematics
Topic: Number of primes...
Replies: 8
Views: 1258

Re: Number of primes...

I believe the constant is called "zero", and its decimal expansion begins 0.00000....

It is odd that the ratio would appear to remain "high" for such large values, but primes do not have positive density on the naturals, so it cannot converge to a positive number.
by Buttons
Wed Feb 25, 2009 4:53 pm UTC
Forum: Mathematics
Topic: Easy Fractals
Replies: 5
Views: 2740

Re: Easy Fractals

Kids these days! When I was your age, we didn't have fractals to draw in class; we just had that S thing.
by Buttons
Sun Feb 22, 2009 6:34 pm UTC
Forum: Mathematics
Topic: Traveling across a square
Replies: 24
Views: 6433

Re: Traveling across a square

This is covered pretty well here.
by Buttons
Fri Feb 20, 2009 5:58 pm UTC
Forum: Mathematics
Topic: Redefining Division, a non-multiplicative inversion
Replies: 6
Views: 859

Re: Redefining Division, a non-multiplicative inversion

While this looks similar to normal algebraic division with the divisor -1, there are some interesting side effects. I dunno about that. All you've done is defined a new operation (let's call it \) such that x\y = x/(y+1). So "dividing" by zero is what we would normally call division by 1....
by Buttons
Fri Feb 20, 2009 4:26 am UTC
Forum: Mathematics
Topic: Straightedge and graph paper geometry
Replies: 25
Views: 2262

Re: Straightedge and graph paper geometry

One nice fact is that any polygon you create must have rational area. (Hint: Pick's Theorem.) I'm not quite sure how, but I suspect it's possible to turn that into another proof that you can't make an n-gon (for n > 4).
by Buttons
Thu Feb 19, 2009 11:09 pm UTC
Forum: Mathematics
Topic: Favorite math jokes
Replies: 1452
Views: 457407

Re: Favorite math jokes

That's not true. Drinking can make one disoriented.
by Buttons
Wed Feb 18, 2009 2:57 am UTC
Forum: Mathematics
Topic: I challenge you!
Replies: 15
Views: 1594

Re: I challenge you!

Funny you should post this today. You didn't happen to go to this, did you?
by Buttons
Tue Feb 17, 2009 6:02 pm UTC
Forum: Mathematics
Topic: Stacking a deck of cards
Replies: 16
Views: 1389

Re: Stacking a deck of cards

Would it be too hard to simply memorize an ordering? I decided a while ago that it would be useful to know a nontrivial permutation of the alphabet, so I memorized the one California generated as a ballot ordering for the recall election (RWQOJMVAHBSGZXNTCIEKUPDYFL), which isn't too hard if you sing...
by Buttons
Tue Feb 17, 2009 2:35 pm UTC
Forum: Mathematics
Topic: Stacking a deck of cards
Replies: 16
Views: 1389

Re: Stacking a deck of cards

Oh, I see. You want to be able to find a given card from the start, not just know what the next card in the deck is. Well, there is the simpler solution of taking multiples of k mod 53, rather than powers. The individual elements are easy to compute, since the nth term is just n*k. But it does have ...
by Buttons
Tue Feb 17, 2009 3:59 am UTC
Forum: Mathematics
Topic: Stacking a deck of cards
Replies: 16
Views: 1389

Re: Stacking a deck of cards

Take a primitive root mod 53 (2, say). Its powers mod 53 will form a permutation on [52] with no "patterns," assuming I'm understanding what you mean by "pattern." That is: (2 4 8 16 32 11 22 44 35 17 34 15 30 7 14 28 3 6 12 24 48 43 33 13 26 52 51 49 45 37 21 42 31 9 18 36 19 3...
by Buttons
Mon Feb 16, 2009 11:48 pm UTC
Forum: Mathematics
Topic: Number of paths in a maze
Replies: 9
Views: 847

Re: Number of paths in a maze

Oh, nice. I love the matrix tree theorem.

But, uh, doesn't that overcount? I thought we want the number of spanning trees in which each vertex has degree 1 or 2. (In other words, the number of "spanning paths.") I could be misreading your reference, though.
by Buttons
Mon Feb 16, 2009 11:29 pm UTC
Forum: Mathematics
Topic: Number of paths in a maze
Replies: 9
Views: 847

Re: Number of paths in a maze

Correct. Though if you remove the clause about rotations and mirror images, it seems to be at least partially answered with A120443. (This is different from NathanielJ's link, in that here we don't assume you start at the top left.)
by Buttons
Mon Feb 16, 2009 11:06 pm UTC
Forum: Mathematics
Topic: 1 + 1 = ?
Replies: 44
Views: 5293

Re: 1 + 1 = ?

You'd rather throw out the rule log xy = log x + log y than accept that e x is not injective? Inverses of noninjective functions are multivalued. There's nothing physics-y about that. I'm all for narrowing the range in a given situation, of course. But I would hardly say that log x = 2pi*i "has...
by Buttons
Mon Feb 16, 2009 9:57 pm UTC
Forum: Mathematics
Topic: 1 + 1 = ?
Replies: 44
Views: 5293

Re: 1 + 1 = ?

Tac-Tics wrote:The trick is it is NOT true that log xy = log x + log y for all real x and y.

Sure it is. It's well known that log 1 = 2pi*i, among other things. There's nothing wrong with the rule that log xy = log x + log y, so long as you don't assume that the result is the only value log xy equals.
by Buttons
Mon Feb 16, 2009 4:55 am UTC
Forum: Mathematics
Topic: Convergent Series question
Replies: 10
Views: 2404

Re: Convergent Series question

Are you suggesting that [imath]\sum_{k=1}^\infty 1[/imath] converges absolutely?
by Buttons
Wed Feb 11, 2009 3:33 am UTC
Forum: Mathematics
Topic: Favorite math jokes
Replies: 1452
Views: 457407

Re: Math joke

zee-bar is more common, I believe. Except in Britain, where they say zed-pub. (Also, I'm just one person.)
by Buttons
Wed Feb 11, 2009 2:20 am UTC
Forum: Mathematics
Topic: Favorite math jokes
Replies: 1452
Views: 457407

Re: Math joke

Nlelith wrote:This might work on a T-shirt if you have an imaginary function become real (too lazy to think of an example but you know what I'm getting at) and underneath have it read "shit just got real."

Thus?
by Buttons
Tue Feb 10, 2009 2:11 pm UTC
Forum: Mathematics
Topic: Favorite math jokes
Replies: 1452
Views: 457407

Re: Math joke

Shit just got complex?

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