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 May 24 comment Compute $\lim_{n \to \infty} \left(\frac{1}{\sqrt{n^3+1}} + \frac{1}{\sqrt{n^3+4}} + \cdots + \frac{1}{\sqrt{n^3+n^2}}\right)$ @GregoryGrant you need to correct the answer. (the $n / \sqrt{n^3+n^2}$ to $n / \sqrt{n^3}$) May 24 comment Compute $\lim_{n \to \infty} \left(\frac{1}{\sqrt{n^3+1}} + \frac{1}{\sqrt{n^3+4}} + \cdots + \frac{1}{\sqrt{n^3+n^2}}\right)$ @Gregory your inequality is wrong. $n / sqrt(n^3+n^2) > 1 / sqrt(n^3)$ May 9 comment Math problems that are impossible to solve I agree with Gerry. I was considered a big surprise when - some thousands of years ago - they proved this, and therefore that there are irrational numbers. May 9 comment Simplify $\left(ab \sqrt[4]{a^{3}/\sqrt{b\sqrt{b}}}\right)^{2}$ 13 x 2 = 26 and 28 x 2 = 56. Where did the two 16 disappear into?. Apr 29 comment How to construct a product set whose complement is not a product set? Why not $A \times X \subset X \times X$ ? Apr 6 comment Is There any formula to calculate automorphism with the spesific graph? Dn x (Sk)^n where k = s-2 I'm not exactly sure about the group itself but the size of it is certainly 2n x (s-2)^n. Matches your 2x3x(3-2)^3=6 and 2x4x(3-2)^4=8 Apr 6 comment Is There any formula to calculate automorphism with the spesific graph? The group seems to be D4 x (S2)^4 Apr 6 comment Inequality involving Square Root The answer is correct but not the solution. Mar 26 comment Seeking guide for project. The "Knot Book" by Colin Adams is my favourite. You should definitely have a look at it if you can find it in the univ. library. Jan 18 comment Why do some other people use dek and el rather than letters as the eleventh and twelfth digits in the dozenal or duodecimal system? "deka" is the Greek word for ten. It looks closer to dek than decem. Dec 18 comment Does this algorithm find prime numbers only? " for verifying that 147 is prime, ..."? The wording does not look appropriate, considering that 147 is not prime. Dec 13 comment Trisecting an angle and another +1 for the conclusion that you must have made a mistake. Dec 13 comment Trisecting an angle An initial 135 degrees angle would also demonstrate the problem quite well. The resulting 3 angles would not be 45 degrees and it's easy to check visually (adding 2 of them would not be equal to 90 degrees) Dec 8 comment Find value of sum of reciprocals of powers of a number @Wood or x=1 (instead of 0.5) Dec 4 comment Why is it that $f(x)$ is even if $f(-x) = f(x)$? Definitions do not require proof. It's like baptizing. I baptized myself ypercube. Therefore ypercube is me. We baptized even functions all those functions f that satisfy f(x) = f(-x) for all x that f is defined. Nov 20 comment How to find a general sum formula for the series: 5+55+555+5555+…? Shouldn't the summation be for k=0 up to n-1? Nov 12 comment Open mathematical questions for which we really, really have no idea what the answer is @pew Added the link above. But he thinks that if we find a proof, it will probably be an existentiaal one, not an actual algorithm, useful in practical applications. Nov 12 comment Open mathematical questions for which we really, really have no idea what the answer is For the record, Knuth said that he thinks P=NP is more plausible, in a recent interview: informit.com/articles/article.aspx?p=2213858 Nov 7 comment Evaluate $\int_{-1}^{1} \exp(x+e^{x})\,dx$ You are fast ;) Nov 7 comment Subgroups of Order $p^2$ in $\mathbb{Z}_p \oplus \mathbb{Z}_p$ You already say that the order of the group is $p^2$. So you have a bag with $X=p^2$ items. You take $X$ items and put them in another bag. How many ways to do this?