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Mathematics

From algebra to calculus, from trigonometry to set theory, it's all here.

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  1. From basic sequences, series and calculus, to measure theory, complex analysis and more advanced topics.

    • 1.2k posts
  2. Set theory, groups and ring theory, linear algebra, and other algebra-related topics.

    • 539 posts
  3. Home to threads on more applied (but non-physical/mechanical) threads; e.g. applied group theory or statisics.

    • 482 posts
  1. Started by YT2095,

    apparently the number "One" is the most frequently occuring in any set of data by 30%. is this True? and if it is, Why is it? I`ve searched the net for it and comeup with very little, but there is a mathematical explaination named after a guy with the 1`st letter "B" in his name (it was noisey and I didn`t catch all the info about it). can anyone help?

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    • 3 replies
    • 1.7k views
  2. Started by dr|ft,

    A sphere of radius 8 cm is circumscribed by a right circular cone. If the cone is to have a max volume, find the height of the cone and the radius of the base of teh cone... I need to relate the radius of the sphere to either the radius of the base or height of the cone, i can't find anything, any ideas people? Vol of Sphere = 4/3 TTr^3 Vol of Cone = 1/3 .TT.r^2.h

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    • 4 replies
    • 7.5k views
  3. Started by abeefaria,

    Anyone here know much about Mathcad, enough to help me set up a table with the erf and erfc functions? I can get the output, but need help figuring out how to make the table the way I want it.

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    • 0 replies
    • 1.1k views
  4. Started by ElijahJones,

    I will try to introduce several methods here. There is security sensitivity to this topic but nothing we do here is likely to approach a real RSA caliber factorization method so we should'nt get visited by NSA.

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    • 12 replies
    • 2k views
  5. Started by Sarahisme,

    Hey, i am stuck on this question, although i think i have done a bit of it already... here is what i have done so far.... we want an [math] N_\epsilon [/math] such that if [math] n \geq N [/math] then [math] |\frac{1}{x_n}-\frac{1}{x}| \leq \epsilon [/math] we know (by the denition of a limit of a sequence) [math] |x_n - x| < \epsilon_2 [/math] now [math] |\frac{1}{x_n}-\frac{1}{x}| = |\frac{x-x_n}{x \times x_n}| = |\frac{x_n-x}{x \times x_n}| = |x_n-x| \times |\frac{1}{x \times x_n}| [/math] so [math] |x_n-x| \times |\frac{1}{x \times x_n}| < \epsilon_2 \times \frac{1}{x \times x_n} [/math] but i am unsure of what to do next. …

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    • 6 replies
    • 1.7k views
  6. Started by Kyrisch,

    Using a stopwatch, a stick, a ruler, and a shadow cast by my house and the sun, I estimated the apparent speed of the sun. Or so I thought. I ended up with a rough number of 75 mm in 5 minutes. Now, doing the math, we get 900 mm in and hour, and 21,600 in a day. That means the sun's light apparently travels 2,160 cm in a day, or 21.6 meters. This can't be right. Can anyone tell me what I did wrong?

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    • 7 replies
    • 2.9k views
  7. Started by iwfc87,

    Hey guys, well, my math problem is below and I need help on it: Determine the maximal subset of R(real numbers) on which the following functions are (i) defined (ii) continuous [math] [x] [/math] is a Gauss bracket of [math] x [/math]. Defined to be the greatest integer (Z) not greater than [math] x [/math]. Eg: x=1.7, [x]=1

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    • 5 replies
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  8. Started by Freeman,

    OK, after reading books on linear algebra, and vector calculus, I have come to tensor transformations. Huzzah! However, I do not have any book to study from(!) so I am rather "sol". I do understand that covariant tensors have subscript lettering and contravariant tensors have superscipt lettering. How do I transform a given vector in covariant and contravariant tensor transformations? I googled it and there were a number terrible websites. Any help would be great!

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    • 8 replies
    • 2.4k views
  9. Started by Sarahisme,

    hey, its been awhile since i could do these, could i have a little bit of help, if there is someone willing out there? Cheers Sarah

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    • 15 replies
    • 2k views
  10. Started by jessica,

    hi finding these questions impossible and was wondering if anyone knew how to answer them!!!.... 1) a linear transformation T:R^6 -> R^6 is known to have characteristic polynomial x^2(x+1)(x+5)^3 determine all possibilities for the minimum polynomial of T 2)let V be and inner product space over C with inner product <,> and let u,v be vectors from V which are orthogonal to each other. prove that ||au+bv||^2 = |a|^2||u||^2 + |b|^2||v||^2 for any complex numbers a and b thank you!!!

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    • 4 replies
    • 1.8k views
  11. Started by herme3,

    What exactly is infinity? Isn't it just a term to describe a number that is beyond our calculation ability? Since the numbers go on forever, wouldn't it be impossible to have a value that is too big to be a number?

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    • 8 replies
    • 2.5k views
  12. Recently I've been reading up on QM and came upon the lovely little thing known as the fourier transformation. I was able to tell that it involved calc, and my physics teacher explained what it did, but does anyone know exactly what level of mathmatics is involved in it? or the specific subjects needed to understand it?

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    • 11 replies
    • 2.3k views
  13. Started by Sarahisme,

    umm here is the question "Here V is a nonzero finite-dimensional vector space: If dim V = p and if S is a linearly dependent subset of V, then S contains more than p vectors. True or False?" Now i am not sure , i could argue either way, although the answers says that it is false. i think it is false because it doesnt say that S is a basis, and so S can have less than p vectors and still be a subset of V. on another note, can a z-dimensional vector space V have a basis with less than z vectors in it? (or is this a related note? )

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    • 3 replies
    • 1.5k views
  14. Started by Sarahisme,

    would anyone be able to give me a hint to get me going with this problem, i am unsure as what i should start by doing... small hint? Cheers Sarah

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    • 21 replies
    • 3k views
  15. Hello... I am currently doing my U.G in electronics... However I am suffering with a networking course which has a tinge of graph theory in it. I feel my graph theory skills should be optimised, but i fail to find a good book which deals with the subject and its networking applications with sufficient rigour. Could anyone direct me to one?

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    • 1 reply
    • 1k views
  16. Started by Psion,

    I figured since I don't want to clutter up this board with a bunch of newly created threads, that I'd post whatever math problems I'm having in here. I suck at math, sadly. The most recent problem I've come across is this: factor each expression completely x^3 - 8y^3 So I tried doing this since: (x-y)(x^2 + xy + y^2) factored: x^3 + 2x^2y + 4xy^2 - 2x^2y - 4xy^2 - 8y^3 Which turns out to be: (x -2y)(x + 2xy + 4y) what I don't understand from this problem is how 4 gets there.

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    • 9 replies
    • 2.1k views
  17. Started by losfomot,

    I am sure this is very simple, but could someone work through this question for me? This is not homework, I just want to learn the steps to do it. x = (4-i)/(1-3i) I am supposed to put it into the form x = a + bi The answer is: x = 7/10 - 11/10 i Thanks for any help you can give me.

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    • 7 replies
    • 1.9k views
  18. Started by Sarahisme,

    hey i was just wondering how you show this... or well if i am doing or done it right? thanks -Sarah ...i'll post my answer in a min, just let me type it up...

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    • 22 replies
    • 3.5k views
  19. Started by Sarahisme,

    i can't quite work this one out... i think the first step is to say that we want to find complex root of this: z^{n} = a but yeah...i dunno...can someone give me a few pointers please Sarah

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    • 49 replies
    • 5.8k views
  20. Started by ed84c,

    Right, Aparantly the chance of England not winning the test today is approx 2-1 Now, in theory that means in say 3 matches England would not win 2 and win 1. But what are the chances of the afformentioned situation occuring. In theory they are certain, but evidently that is not the case.

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    • 4 replies
    • 1.5k views
  21. yay! i might have actually got this one right hopefully, how'd i go... i reckon R = 2 , where R is the radius of convergence of the power series....

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    • 6 replies
    • 1.6k views
  22. Started by Sarahisme,

    hi, yet another one of my questions i can't quite figure out how to prove this....i can see its true, but i just don't know how to write it out formally :S -Sez

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    • 22 replies
    • 3.5k views
  23. Started by Crash,

    Ok, i got a couple of probs. how do i prove if a series is divergent or convergent? and what is the nth term test? can someone please explain it to me?

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    • 3 replies
    • 1.7k views
  24. Started by Psion,

    I don't know the latex symbol to get long division symbols but hopefully someone can figure this out for me. I've been doing pretty good until I came across this problem: (x^3 + 1 + 2x) / (x^5 + 3x + 2) Answer is: [hide]x^2 - 2 + [(-x^2 + 7x + 4) / (x^3 + 2x + 1)][/hide] I was going to go in depth about this, however, I don't see the latex symbol that closely looks like the square root symbol for division.... It's very obvious to me that I need long division. I just didn't know how to solve the problem, that's all. I don't understand the long division processes used in this. Long division in plain numbers is somewhat easy, however, this p…

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    • 8 replies
    • 2.9k views
  25. Started by anthropos,

    Here's a maths question I have found in a maths test. Solve for x. Give me some hints please...I am clueless. Anyway ignore those green squares.

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    • 10 replies
    • 1.8k views

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