Mathematics

Hello everyone, I want to make sure I understand the Cartesian product of two sets. Let A = {1, 2} B= {3, 4} Then A X B = {(1,3),(1,4),(2,3),(2,4)} Is that correct? Thanks

why pi is used in math?i mean why always 3.14....

Hi all, In my work we have to run tests whose input parameters are in 3 dimensions, forming lines across a grid, like so: What I want to know is, what is the best way of quantifying the spread of these lines? If I were to use the extreme points to plot a cuboid I think that would overestimate the parameter space over which the experiments were run. I have also considered calculating the convex hull, using the extremes but I feel this might also lead to the same problem, albeit with a smaller overestimation. I need to demonstrate that the lines are well spaced out from one another, perhaps by the angles between the lines. Is there already a way of quantify…

i got a question from a class teacher,nobody in the class or in the higher class can do it,because,number system is not in our syllabus.but i wanna know,let a=<3^n+2n+1>,where n can be any of positive numbers.the question is for which values of n;a can be a perfect square?oh,can anyone tell me about a book of number system where i can learn by ownself?

I'm doing work for math class (high school level), and we're currently on linear systems of equations. Simple linear systems like: ...as taken from my text. Some of several methods we're expected to use are elementary substitution and elimination (there are more efficient ways, but these are the focus for now). What's peculiar is that for some of the problems, it takes me 3 or 4 attempts to finally get a working answer when using these methods. I'm not sure why, but I often derive an answer which only solves one or two of the equations, rather than all the equations in the system. This is pretty strange, since whenever this happens, I can never pick out what I di…

I twist my outer Obloid shape 90 degrees, No matter how I think, including using logic and lateral thinking, I can not make my shape fit. I have come to you, the maths department of forum, for your help. NO ONE, seems to understand my lateral thinking.

Hello everyone, For as long as I have known about the constant [latex]e[/latex], I have been in awe of its many uses and at times strange properties. Now I know its definition as a limit and as a series, but I have never quite understood just what makes [latex]e[/latex] so special, beyond the fact that it helps us solve problems. So my question is: what makes [latex]e[/latex] so significant to the overall study of mathematics? I hope that makes sense. I look forward to others perspective on this. Thanks

If 1 dimension has length. 2 dimensions has area. 3 dimensions has volume. what does 4 dimensions have?

Dear all, I'm interested in learning more about the foundations of math. Any reading suggestions? Thanks, kmerfeld

I'm doing my thesis now about Knowledge Management (KM) readiness assessment in organization. I'm thinking to use fuzzy logic for doing the statistic, and my lecturer advised me to use Fuzzy Multi-Criteria Decision Making (FMCDM). By the way, my research steps are: arrange the questionnaire using Likert scale, then weighted it using FMCDM method. But even I've read many many papers about FMCDM, I still couldn't find and still stuck about how to weight the scaled questions using this method? I hope you all can help me to solve my problems.

Hello everyone, I want to prove that for postive integers x, y, y is not equal to x+y. I want to do this using the WOP. Here's what I have done so far: Suppose for some postive integer x, there exists a y st y y+x. By the WOP, there exists a smallest x0 st y=x0+y. Now I think I may have to apply the WOP again, but am not sure. Any advice? Thanks a lot, Kevin P.S. A little help using special BBC code. I'd like to use LaTex but when I try to do the not equal sign it shows up as: [latex]\ne [/latex] How do I get rid of the < br > ?

Just curious as to whether there is an exact formula to calculate pi using algebra.....Disregarding c/d or any approximation such as 22/7. Is there any relation to primes and while im asking is there any formula for finding an Nth term prime. I.E. a pattern showing where a prime will crop up. Im currently trying to formulate an equation that finds pi using only numbers 1-4. Where a = 1, b = 2, c = 3 and d = 4; something like; (d/c) * ((d/c) + (c/b) * ((d/c) / (c/b)))); Makes something within 2 decimal places, obviously this is just random and at some point must happen but im curious whether a formula along these lines already exist and can prove pi in purely …

The little I know about primes is that there is no any 'Systematic Formula' for obtaining prime numbers in either ascending or descending order.And the whole world is in a delima as wheter there is a limit to primes or NOT.That is whetther there is a HIGHEST PRIME NUMBER. I have Good, Better and Best formulae for generating Prime Numbers systematically. TRY THE GOOD ONE: P=7d-4 Where: P=prime number(Needed) d=odd number(Chosen) Example: At d=5, it means; P=7(5)-4=35-4=31 there are a few exceptions for the Good formula. Questions and contributions are welcome

On reading this exchange (part of a long thread on definition of religion) - something occurred to me. Do the rules governing regular 3-d solids change in non-euclidean space? http://en.wikipedia.org/wiki/Platonic_solid http://en.wikipedia.org/wiki/Archimedean_solid http://en.wikipedia.org/wiki/Euler_characteristic etc...

I have a set of results from an experiment I did recently in the lab where one array of results is for the variable [latex]\theta[/latex]. In order to obtain a graph from which I can analyse the results and obtain a value for the electron mass I must take the cosine of this variable, to give me the following data: [latex]\cos \theta = [0.94, 0.77, 0.50, 0.17, -0.17, -0.50][/latex] Now, the errors on theta are plus/minus 0.5° and so using the standard error formula and assigning a variable y to the cosine of theta such that [latex]y = \cos \theta[/latex], I obtain the error on y (which will be the error on cos theta) as: [latex]\sigma (y) = \frac{\partial y}{\p…

Okay so recently ive been studying computer graphics, polygons, triangles, vectors, circles etc, alot of trig and cartesian matrice addition (with trig functions in one matrice to find the position of the new triangles etc). I dont have great background knowledge of trig so i revised over some of the stuff i did back 6-7 years ago which is just SOHCAHTOA and circle trigonomic graphs. After i fully understood the euclidic geometric axioms (or the area's i needed for my specific graphic module), i got to thinking alot about triangles. First i'd like to offer that if you split a circle into 4 equal parts by folding it in half and half again, your left with 4 right an…

There are 25 bicyclists and just 5 bicycles. Of all these we need to find best 3 cyclists. How many races should be held to determine top three winners and why? <link removed>

OK I admit I thought I was losing my sanity when I thought of this, but then I realized people thought Galileo was crazy when he said that the Earth went around the Sun. I am a (fairly)good mathematician and I know better than to question integer division by zero is undefined, but what about 0/0. Basically, for the past one week I was thinking about 0/0. Not integer division by zero but only about zero divided by zero. To prevent "You must be out of your mind" replies, I would like to state the.... uh.... rules first. Here's my theory. f(x) = x/x is a constant function giving the value 1. Therefore, 0/0 is also 1. IF you're going "OMG, Gasp.... what a sacrilege…

Hi everyone, I'm having a little trouble using the xcorr instruction in matlab, and honestly I don'y quite get how it works. Now I know that when you type l=xcorr(u,v) it creates a new vector that containg the entire correlation sequence. But say I want to calculate [y(t-1)*y(t-2)]/N, whete t=1,...,N. How do I do that using the xcorr instruction? Thanks, PM

In classical maths from Euclid believed that a triangle is 180º and that in 1 point only can travel a parallel to other. – http://en.wikipedia.org/wiki/Parallel_postulate So determine that “At most one line can be drawn through any point not on a given line parallel to the given line in a plane” Lately Non-Euclidean geometry says that “Either there will exist more than one line through the point parallel to the given line or there will exist no lines through the point parallel to the given line” – http://en.wikipedia.org/wiki/Non-Euclidean_geometry#History According to this new geometry (has more that a century), by a point can exist more that one line, so acc…

Going to throw my laptop out of the window soon. Don't think it will help though. Little things are tripping me up, and I can't get answers for them anywhere I search. I have a standard deviation value, I have a graph with a point plotted. How to I add an error bar to this? I mean, the SD value is 0.9. Do I draw the bar going 0.9 above and 0.9 below the point? Or do I have the point in the middle of that error margin, and the error bar going 0.45 above and below my point on the graph? I hope it's the latter of the two, or else I have to draw this graph for the 100th time because it's not big enough for these error bars.

I'm looking for a book or some kind of course on "wave mathematics". I'm familiar with basics, like wavelength, frequency, amplitude, interferrence and all that, but I want to further improve my understanding of this subject.

Manipulating Euler's equation I got this equation (-1)^(1/pi)*e^i=1^(1/pi) To the best of my knowledge this equation is correct. If it is, why would Google calculator give a complex value for for the left side of the equation when the actual value should be 1.

My take on the original proof by Euclid, which shows that there are infinitely many prime numbers. A good introductory proof I believe... Now questions regarding the nature and methodology of the proof... What demonstrations are involved in this? I'd like to think: proof by exhaustion (whole) and proof by absurdity (2.B). Can case 2B also be shown as a proof by contradiction, where it implies K is not in L (a direct contradiction of the assumption)? BTW, I'm a student. When I first encountered this theorem, this was my first real exposure to an elementary proof and I found it beautiful. I wanted to paraphrase it so that things would be a little more obvious…

In your opinion, what equations, solutions, or sets are the most elegant math equations ever solved or conceived of? Personally, I like Euler's identity. That is, e^(i*pi) +1 = 0. The way it is proven is also something to marvel at too, since it comes directly out of complex analysis.