Mathematics
From algebra to calculus, from trigonometry to set theory, it's all here.
Subforums
-
From basic sequences, series and calculus, to measure theory, complex analysis and more advanced topics.
- 1.2k posts
-
Set theory, groups and ring theory, linear algebra, and other algebra-related topics.
- 539 posts
-
Home to threads on more applied (but non-physical/mechanical) threads; e.g. applied group theory or statisics.
- 482 posts
-
Ground-up mathematical tutorials.
- 1 post
2404 topics in this forum
-
A few years ago, I had a math class, which I needed a TI-83 calculator, for. I don't have the class, anymore, but I bought the calculator, myself, so I still have it. However, of all the nifty features that the TI-83 has over traditional "pocket" calculators, it seems to lack a memory function! Pocket calculators allowed you to save a number to memory. You could also add and subtract from that memory. If you wanted to multiply the memory by something, there was a way to do that. This allowed you to use a commonly-recurring, but large number, without having to tediously punch in that same number over and over again. How do I do that, on a TI-83?
-
0
Reputation Points
- 1 reply
- 2.1k views
- 1 follower
-
-
Now... When i first heard about this I thought it was a joke but i've seen references to it in several places now. Is it real and can anyone explain what it is intended to do? ( if it does indeed exist?) http://en.wikipedia.org/wiki/Cox-Zucker_machine http://en.wikipedia.org/wiki?title=Talk:Cox-Zucker_machine http://improbable.com/2008/08/12/the-cox-zucker-machine/
-
0
Reputation Points
- 2 replies
- 4.9k views
-
-
Ok so to start out, I was given a puzzle to solve under the conditions that i could not solve it by using a scientific calculator. So hitting Sin(x) is not an option. I was started out with a circle as a base. The circle has a Diameter of 6.5 meters and an idea of putting 80 points along the edge of the circle with the same distance between each of them. I need to find the distance that is between these points, Not the arch curve but the straight line between them. best way i thought of how to do that was to make a triangle, using the radius for 2 of the sides and finding the link the third and final side through law of sines and law of cosines. Side a=3.25 S…
-
0
Reputation Points
- 5 replies
- 7.5k views
- 1 follower
-
-
I've heard of this mathematical theorem but could someone explain it to me, in very, very short words and simple sentences?
-
0
Reputation Points
- 11 replies
- 5k views
-
-
how can i calculate the surface aria of a parabolic mirror
-
0
Reputation Points
- 1 reply
- 1.3k views
-
-
104 x 104 +4 = 108 4x4 = 16 104 x 104 = 10816 109 x 109 +9 = 118 9x9 = 81 109 x 109 = 11881 A little trick I use.
-
0
Reputation Points
- 13 replies
- 3.6k views
-
-
Is this really possible? I doubt I can explain much about what I am interested in to the first man whom I see on the street. Maybe that is a reflection on me rather than the subject matter. Any thoughts on this?
-
0
Reputation Points
- 5 replies
- 1.7k views
- 2 followers
-
-
Here is a question I have always wondered how the answer is correct, because I can't manage to make it seem right. A chap at the fair is tring to find a prize that is hidden in one of three caskets. He chooses a casket, whereupon the man running the stall opens one of the other cases, which is empty. He then asks the chap if he wants to stick with the casket he chose originally, or switch to the remaining one. which casket will give the chap the greatest odds of winning? The answer in the back of the books states that if he switches, his chances of winning are doubled. so the chap should take the remaining casket. This always seems quite odd to me. It s…
-
0
Reputation Points
- 11 replies
- 3.4k views
- 1 follower
-
-
I've seen it played numerous times in the Clock Game. The goal is when you are faced with a ton of possibilities, and you try to eliminate as many possibilities as you can, so that you are left with only one possible answer. This can make the Clock Game easy to win, even if you have no earthly idea what the price of the item is. "five hundred" "Higher." "seven fifty" "Higher" "Nine hundred" "Lower" "Eight hundred" "Higher" "Eight fifty" "Higher" "Eight eighty" "Higher" "Eight ninety" "Higher" "91, 92, 93, 94, 95, 96, 97, 98, 99-" "THAT'S IT!" The fridge is worth $899. The Clock Game is the most common example, but not the only one, where this …
-
0
Reputation Points
- 3 replies
- 1.8k views
-
-
While using several operators(e.g.grad,div,curl) we often separate them and treat them as vectors in their own right,performing most algebraic and vector operation on them.How is this possible? are not operators and their operands inexorably linked together.In order to separate them we would need to define a whole set of specialized rules just to use them. This is not an isolated example several times while solving differential equations we replace the differential operator with a variable ,say 's'(and hence this technique in some areas gets its name as the s-operator method) (ref:http://en.wikibooks.org/wiki/Circuit_Theory/Second-Order_Solution)and proceed to manipulat…
-
0
Reputation Points
- 1 reply
- 1.8k views
-
-
The title speaks for itself. I guess the question should be narrowed down to irrational numbers, since the rest are all rationals. I'm leaning towards no, although that's just intuition speaking. Note that I'm not asking if we can find a closed form expression for a given number; just if it always exists.
-
0
Reputation Points
- 6 replies
- 1.9k views
-
-
Any thoughts would be appreciated.
-
0
Reputation Points
- 7 replies
- 2k views
-
-
Take a 2D enviroment that contains a straight line where the x and y coordanates of the two ends of the line are known and also the position of a car and the angle it is facing (7 values). The car moves forward in a straight line. Is there a simple, reasonably computationally fast way to work out if the car ever intersects (crashes into) the line? Would it become much more complicated if one of thease additional pieces of information was needed? either where did the intersection occur or given multiple lines which one was intersected first.
-
0
Reputation Points
- 2 replies
- 1.3k views
- 1 follower
-
-
number system goes from 0 to ∞ (and 0 to -∞ for negatives) as far as i know nothing in our physical world holds no mass and all matter is energy (correct me if i am wrong) now, my question is: can nothing be calculated?
-
0
Reputation Points
- 10 replies
- 2.5k views
- 1 follower
-
-
I am getting on in years and since retirement I have been giving Fermat's Last Theorem some thought. I believe most people are attempting to solve this puzzle in the wrong way. There may be NO good reason why (say) A^3 + B^3 = c^3 should not have a whole number solution. However there is a very simple reason why the relevant "wrong sum" A+B=C cannot logically be deduced. Please note, I am not saying it cannot exist - only that there is a simple reason that it cannot be deduced. The reason applies to all powers>2. Perhaps this was Fermat's starting point!? I should be interested if this thought gets any response. More later - perhaps a conjecture if not quite a…
-
0
Reputation Points
- 24 replies
- 6.1k views
-
-
hellooo all . I just wanna hear from you all people , suggesting me some standard books with author to understand all mathematical concepts with physical realisations and practical Examples....for ALL MATHEmatical topics in PURE and APPLIED mathematics ... must feel happy to start with nice books suggested by friends over here.... Thanks in Advance by non LINEAR +-*/
-
0
Reputation Points
- 2 replies
- 1.3k views
-
-
If 45lbs of 45F water plus 7lbs of 85F equals 52lbs and 51F water. How much lbs of 45F and 85F do you need to get 52lbs of 65F water and what is the formula for achieving it?
-
0
Reputation Points
- 12 replies
- 2.8k views
- 1 follower
-
-
Hi, Can anyone help me with this: Let Bqnr be an arbitrary tensor. [Here q n are contravariant indices and r is covariant index.] Suppose we have a quantity X(p, q, r) such that X(p, q, r) Bqnr = 0. Is X(p, q, r) identically zero? Thanks a lot in advance. john_mawlai.
-
0
Reputation Points
- 2 replies
- 1.3k views
-
-
0 / 2 = Half of 0 Half of 0 / 2 = Quarter of 0 .5----------5----------5 ...4--------4--------4. .....3------3------3.... .......2----2----2....... ...........1-1-1........... 5-4-3-2-1-0-1-2-3-4-5 ...........1-1-1........... .......2----2----2........ .....3------3------3..... ...4--------4--------4.. .5----------5----------5 I don't understand why '0' is the end. 0 is open to each way, it shouldn't only move forwards "0 1 2 3 4" in this fashion. We created that system, it's not the natural system.
-
0
Reputation Points
- 68 replies
- 12.7k views
-
-
Hello. Well known, x2= 4py : http://dy185677.en.ec21.com/C_180_Cm_Satellite_Dish--2988376_3112840.html has the focus at its axis, and the axis aims direct to the radio sorce, as learned decades ago. But this one has the focus offset from the axis : http://www.bikudo.com/product_search/details/13760/satellite_dish_antenna.html Is the radio source not collinear with its axis ? How does the latter aiming works? Is there any ray-tracing graph on the web for an offset focus parabola you can link please ? Never came across that second version in my years of analytical geometry For both antennas, the focal point is, that, a point. If the radio source d…
-
0
Reputation Points
- 3 replies
- 1.8k views
-
-
Hi all, (I wasn’t sure should I post this to Physic or Math forum. I decided to go for math.) Can anyone help me understand ‘connection’ between value and a physical unit. Somehow I always assumed that there is ‘invisible times’ operator between them (anticipated multiplication). For example when I write ’20 kg’, a always assumed it actually means ‘twenty times a kilogram’. But now I am not so sure anymore – for example, you cannot write ‘kg 20’. It doesn’t mean the same (or does it?). In some cases, it is beneficial to think about units as factors. For example one can write the following expression: ‘20 W * 3 s’ (twenty watts times three se…
-
0
Reputation Points
- 3 replies
- 1.3k views
-
-
I'm not very familiar with checkers, and even less so with chess. But after I heard of polar coordinates (has to have been more than half a year ago now) and its nature of being analogous to rectangular ones... I imagined, would you be able to play a game that uses a rectangular-coordinate grid... whether chess, or checkers, or something else... on a polar-coordinate grid?
-
0
Reputation Points
- 1 reply
- 1.5k views
-
-
In this link. What do the #'s in the solution mean? Also there could be 0 to 4 solutions for given values of x, q, w, r, t and u. How do the equations provided return those up to 4 values?
-
0
Reputation Points
- 3 replies
- 1.5k views
- 1 follower
-
-
What is the correct thing to say when speaking of a curved Reimannian geometry: 1. The base manifold is curved, not the tangent bundle over it. 2. The tangent bundle is what's curved, not the base manifold. 3. The curvature of the base manifold is "induced" onto the tangent bundle over it. As a result, both are curved in the same way. Huh?
-
0
Reputation Points
- 5 replies
- 2.4k views
-
-
Based on the paper Recursive Binary Sequences of Differences by R. M. Richman, an article on the Guardian website tells us how to pour the perfect [two] cup of coffee. I think it was Alfréd Rényi who said "A mathematician is a device for turning coffee into theorems." The result is fairly intuitive: if there is a flavour gradient in the coffee pot then the average of the top and bottom should match the strength of the middle, when you're dividing the pot into two cups - assuming a well behaved distribution of flavour (I don't think you could apply the same principle to fairly sharing a bottle of beer, since there are no virtually dregs in the top or middle). T…
-
0
Reputation Points
- 4 replies
- 1.8k views
-