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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
  1. Started by redfreakyppl,

    So I'm doing this science fair project & its due SOON. Its about the genotype (the gene make-up basically) of red hair. I'm trying to come up with all the possible combinations of the genes, but I can't figure out the right equation/formula. Here's the deal: There are 8 alleles for hair color. HHHHHHHH or hhhhhhhh or Hhhhhhhh or hHhhhhhhh or HHHHHHhH, etc. How do I find the # of combinations???

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    • 2 replies
    • 1.3k views
  2. Started by RyanJ,

    Fractals - any real uses? I love fractals, the question is are they useful for anything? I knowthey preduct certain shapes in nature but do they have real uses or are they just pretty patterns? Cheers, Ryan Jones

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    • 16 replies
    • 3.1k views
  3. Started by caseclosed,

    This integral Tan(x)^3+Tan(x) doing it by hang gives Tan(x)^2/2 Mathematica gives Sec(x)^2/2 so why the difference, are both correct, how to get the mathematica answer by hand?

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    • 6 replies
    • 1.7k views
  4. Started by kaseyface,

    My problem is Simplify: [use absolute value symbols if necessary] Squareroot 75a2b3c.

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    • 4 replies
    • 1.3k views
  5. Started by caseclosed,

    how to differentiate sin(x)^x for 0<x<pi/2

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    • 2 replies
    • 1.1k views
  6. As a simple example. If I have a 4 balls, red, yellow, blue and green, and there are 4 places in which I could place these balls, lets say left, left middle, right middle and right. How do I figure out how many combinations of arrangements there could be? I thought it was multiplying the number of spots by how many different kinds of balls could be in one spot. However that gives me 16, and when I start doing it in my head I realize it's way more then that. If that's two hard to understand then, I want to see how many of these there are: red, yellow, blue, green yellow, blue, green, red blue, green, red, yellow etc etc After that, how bout a bigger kic…

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    • 8 replies
    • 3.4k views
  7. Started by the tree,

    Is there someway that I can work out mod values without a this button?

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    • 12 replies
    • 12.8k views
  8. Started by BigMoosie,

    Given 3 points in 3D space as cartesian coordiantes (a triangle) I need to calculate the normal for a 3D graphing program I am making. I haven't done any calculus that might help with this and I don't know about linear algebra so Wolfram's solution is of no help: Can anybody please translate this into an algebraic solution for me? Thankyou.

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    • 1 reply
    • 1.5k views
  9. I'm trying to find: [math]\int_{0}^{12}12x^{\frac{1}{2}}-x^{\frac{3}{2}}\cdot dx[/math] Which I thought was [math][12\times \frac{1}{1/2} x^{\frac{2}{3}} - \frac{1}{3/2} x^{\frac{5}{2}}]_0^{12}[/math] Which I simplified to [math][24x^{\frac{2}{3}}-\frac{2}{3}x^{\frac{5}{2}}]_0^{12}[/math] Which comes to aprox. 207. But my textbook tells me that the awnser should be around 133. Can anyone spot where I went wrong?

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    • 5 replies
    • 1.3k views
  10. Started by kkris1,

    I have a proposition to prove FLT See attachement Fermat_Theorem1.doc

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    • 7 replies
    • 2k views
  11. Started by Trurl,

    Hello, I have been away form SFN since Feb 7th. I have been busy working on things. But I am trying to do a math contest on my site. It is free and I am not selling anything. I just want to share ideas. See www.constructorscorner.com for more information. It runs from May 1st to July 30th Hope to see you there.

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    • 0 replies
    • 890 views
  12. Started by paganinio,

    What is college math like? I have a few questions. 1, Why is my favorite high school olympiad math contents not here? For example, where's number theory? Where's solid geometry? Where's trigonometry? Where's.....? Do they just disappear in college? 2, this is a much more important question. I FALL FOR HIGH SCHOOL MATH OLYMPIAD PROBLEMS. I enjoy the beauty of problem solving there. Am I likely to fall for college math too? You might say "Sure!" But I've read some college math books--they really look quite different. I suppose that every problem solving fan has a BRAIN LIMIT, and she will only feel comfortable when she's solving problems within that limit. No matt…

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    • 4 replies
    • 2.1k views
  13. I'm attempting to create a quiz with the first 8 answers with the possible answers of any of up, down, left, and right... From doing research, I understand this is possible for graph sketching. Is this true? I would like to make a believeable college level simple quiz/test that has these answer possibilities for the first 8 question. Please let me know, thanks.

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    • 1 reply
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  14. O My God. The Golden Ratio. Its quite an interesting subject. Its defined as: [1+(Sqaure root of 5) ]/2. In words, 1 plus root 5, all over 2. In symbols, the value is represented by the greek letter, phi. Lets cut to the chase, I just recently attained a calculator that computes to 5011 digits. The value of the golden ratio is 1.618033988749894848204586834366 to 30 decimal places. Anyway, I noticed that the recipricol, or phi^(-1), is phi - 1. Yes, 0.618033988749894848204586834366. And its not a coincidence to 30 decimal places, wen computed to 5011 decimal places, same result, phi^(-1) =phi - 1. Can anyone explain why or how..or what ever.

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    • 12 replies
    • 2.2k views
  15. Started by Sarahisme,

    Hi hmm...i think i have solved this problem but neither of my 2 answers look like a Laguerre polynomial..... problem: my solutions: :S Sarah

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    • 3 replies
    • 1.4k views
  16. Started by Sarahisme,

    Hi all, would anyone be able to give me a bit of help with this problem: this is what i have done so far (i am now stuck ): thanks Sarah

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    • 1 reply
    • 1k views
  17. Started by Kedas,

    (Dy)² = (a-y²) with y(0) = 0 How do you solve this? Matlab gives these solutions: syntax: dsolve('(Dy)^2 = (a-y^2)','y(0) = 0') y=tan(t)*(a/(tan(t)^2+1))^(1/2) and y=-tan(t)*(a/(tan(t)^2+1))^(1/2) But these solutions are periodic if you look at the diff. equation: when y²=a then y should stay constant (not periodic) can anyone help?

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    • 15 replies
    • 3.5k views
  18. Started by Meital,

    Has anyone studied Differential Geometry from Do Carmo's book, Riemannian Geometry? I am trying to work problem 4 page 57, but I don't even know how to start. I will scan the problem and post it laer.

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    • 0 replies
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  19. Started by said_alyami,

    There is a new theory that may end the endless debate about 1=0.999... the whole theory can be found in this link http://www.geocities.com/humood_theory here is a Quote about cracking the famouse proof: Proof (A) x=0.999... 10x= 9.999... 10x-x=9.999... - 0.999...=9 9x=9 x=1 All the theory and results can be seen in the link: http://www.geocities.com/humood_theory For comments please write it here in this forum or send it to the e-mail said_yam@yahoo.com

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    • 2 replies
    • 1.7k views
  20. Started by Cloud,

    I'm in the middle of revision for my final GCSE maths exam. So far its been alright but today I've come across something that is not covered in any of the books I'm using. I'm assuming its an A* question (since "Introduction to modelling" comes up right at the end of one of the revision textbooks.) Here's the question - d = av + bv^2 Find the values of a and b co-ordinates on the expotential graph - (40,120) (60,240) I know the answer is (because they are provided in a separate booklet) a = 1 b= 1/20 Whats the methodology? I know that for a straight line - finding the gradient would give me the answer. I've tried rearranging the equat…

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    • 5 replies
    • 2k views
  21. Started by redfox,

    I need to express blood pressure in terms of kPa. The conversion is 1kPa - 7.5mmHg, or .133 kPa - 1mmHg, but how would this be expressed? Just kPa subsituting mmHg, ie kPa/kPa?

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    • 4 replies
    • 2.1k views
  22. I learned to use this way instead of the others an+1/an so when the ratio get smaller and smaller for n>1 does that mean it is decreasing? and not increasing nor decreasing when the ratio stay same for all n>1 like (x^2+2x)/(x^2+2x+2).

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    • 0 replies
    • 1k views
  23. Started by dstebbins,

    Suppose I have x number of items. I am instructed to put them in groups of y items, such as groups of two or groups of three. Is there an equation that I can plug these variables into to figure out all possible combinations? Thanks.

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    • 16 replies
    • 2.6k views
  24. Started by caseclosed,

    how do I find the upper and lower bound of this sequence? (2^(n-1))/(n+1)!

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    • 6 replies
    • 8.9k views
  25. Started by Mace Sin,

    Addition is an axiom of mathematics, or am I wrong? I heard that the Peano Axioms can prove 1+1=2, but I don't really know why or how. Can any of you more advanced students dechiper this? (I'm only a freshman in high school, remember, and it's frustrating to not be educated higher in math.) So, if anyone can relate this to me, I'd be grateful.

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    • 12 replies
    • 2.9k views

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