Recent content by Kummer
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Multiple integration + Centroid Help.
You first integrate with z, that gives you rz in the inside. Using Fubini you get (meaning evaluate the integral) r\sqrt{6-r^2} - r(r^2) and now continue with r and theta.- Kummer
- Post #2
- Forum: Calculus and Beyond Homework Help
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Proof that Log2 of 5 is irrational
\log_2 5 = a/b so 2^{a/b} = 5 \implies 2^a = 5^b. Now use unique factorization.- Kummer
- Post #2
- Forum: Calculus and Beyond Homework Help
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High School What is the Study of Mathematics?
I will begin by saying how much I dislike it when non-mathematical philosophers think about math. There are many threads in the mathematics forum like this and they belong in the philosophy forum, so one good thing about this thread is that it at least is in the philosophy subforum. I am not...- Kummer
- Post #25
- Forum: General Math
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Does xn Converge? A Comparison Test
Non-zero constant. Not to offend you but that is what I like to call a "physics-type mistake".- Kummer
- Post #5
- Forum: Calculus and Beyond Homework Help
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Graduate Polynomials and function space over fields
Here is a little something to add to what matt-grime was lecturing about. Theorem: Let |F|= \infty and f(x) be a polynomial if f(\alpha)=0 for every \alpha \in F then f(x)=0. Proof: Let \deg f(x) = n (assuming f(x)\not = 0) then f(x) can have at most n zeros. But it clearly does not for...- Kummer
- Post #5
- Forum: Linear and Abstract Algebra
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Does xn Converge? A Comparison Test
\frac{1}{n+n}\leq \frac{1}{n+\sqrt{n}}- Kummer
- Post #2
- Forum: Calculus and Beyond Homework Help
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No Topology Subforum? Discussing on General Maths
Place Number theory with Algebra. That makes it better.- Kummer
- Post #29
- Forum: Feedback and Announcements
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Finding the Residue of an Expression with a Constant
In what contour? And what is k? Note if k is zero then it becomes 1/e^z which is analytic. But if k!=0 then there is a singularity which depends on the contour.- Kummer
- Post #2
- Forum: Calculus and Beyond Homework Help
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Graduate How Do Riemann and Lebesgue Integrals Compare in Integration Theory?
The delta function cannot be used for a conterexample about theorems about intergration. Because it is not a "function" eventhough it is called a function, rather it is a Schwartz distribution so the known results about integration might not apply to it.- Kummer
- Post #19
- Forum: Topology and Analysis
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Graduate Prove (1+x^2)(1+y^2)(1+z^2)/(xyz)>=8 with x,y,z Positive Real Numbers
Yes he did. I should be more careful lest someone accuse me of stealing answers. I deleted my post otherwise it does not look good. -
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Is it Possible to Teach Yourself Advanced Math Topics?
Most of what I know is self-taught, so there really is nothing amazing about teaching youself. All you need is motivation.- Kummer
- Post #7
- Forum: STEM Educators and Teaching
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Undergrad Galois theory text for second semester undergrad algebra
I really like the algebra book by Blair. It has Galois theory in it. It is better to use Morandi but he is GTM.- Kummer
- Post #3
- Forum: Linear and Abstract Algebra
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Graduate Example of f integrable but |f| not integrable
If f is a bounded function on [0,1] which is integrable then |f| is integrable on [0,1]. It is a simple theorem to prove. -
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Graduate Books for Analysis & Physics: Advice Needed
How well do you know undergraduate analysis? Do you know the following topics: Completeness property Limits of sequences and delta/epsilon, Cauchy sequences Subsequences Limsups and Liminfs Continous functions, delta/epsilon definition, sequence definition Properties of continuous... -
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Proving a polynomial is constant
@ehrenfest. It really is not so hard. If n is a number in {2,3,...,100} it not a prime number then we can write n = p*m where p is a prime number. So for any n there exists a smallest possible prime divisor. Given any n the smallest prime divisor is 7 because it cannot be 11 because if it were...- Kummer
- Post #14
- Forum: Calculus and Beyond Homework Help