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Don't have much time these days...


Oct
25
answered Bounding the integral $\int_{2}^{x} \frac{\mathrm dt}{\log^{n}{t}}$
Oct
25
answered How to prove this binomial identity $\sum_{r=0}^n {r {n \choose r}} = n2^{n-1}$?
Oct
25
revised slipping rod on moving truck
added 29 characters in body
Oct
24
comment How to prove $\cos \frac{2\pi }{5}=\frac{-1+\sqrt{5}}{4}$?
Also look up Kastelyn's method on counting the number of tilings of a 2mx2n chessboard with 2x1 rectangles. Choose m=1 and n=2 for this particular problem.
Oct
24
revised Find an infinite set of positive integers such that the sum of any two distinct elements has an even number of distinct prime factors
added 258 characters in body
Oct
24
answered Construction of an infinite set such that any two number from the set are relatively prime
Oct
24
comment Strange Case in Self-Complementary Planarity
This looks like homework. Please consider tagging it as such.
Oct
24
comment Why is $(x^2-2)/(2y^2+3)$ never an integer for any integers $x$ and $y$?
+1: For an interesting question and showing your prior work.
Oct
24
comment Number of integer solutions in [0,10]
Perhaps we can close this as a dupe of math.stackexchange.com/questions/4632/… or maybe math.stackexchange.com/questions/4643/…
Oct
23
comment Find an infinite set of positive integers such that the sum of any two distinct elements has an even number of distinct prime factors
@Qiaochu: Thanks, I was thinking that that would be a hard homework problem and hence gave a hint for the possibly easier part of proving existence! I have deleted my answer.
Oct
23
awarded  Citizen Patrol
Oct
22
comment Find an infinite set of positive integers such that the sum of any two distinct elements has an even number of distinct prime factors
@QIaochu: I am curious. Does the problem ask to find such a set or just prove its existence?
Oct
22
revised What is the optimal angle when throwing a stone on a slope?
added 771 characters in body; edited body
Oct
22
answered What is the optimal angle when throwing a stone on a slope?
Oct
22
answered Find an infinite set of positive integers such that the sum of any two distinct elements has an even number of distinct prime factors
Oct
22
comment What is wrong in my proof that 90 = 95? Or is it correct?
@Matt: I believe Isaac knows about the latex. The ∠ is an html escape code. Unfortunately, I don't think that exists, though.
Oct
22
comment Compute the Fourier transform of $f(t) = \sin t$?
Did we finally get our name changed, to getyourhomeworkdone.com?
Oct
22
comment Find an isomorphism from the octic group $G$ to the group $G'$
This looks like homework. Please consider tagging it as such.
Oct
21
answered $\sum\limits_{n=0}^{\infty} \frac{1}{(2n+1)!}$ converges?
Oct
21
comment How to solve $ \int_0^{\pi} \sin{2x}\sin{x} dx $?
Writing $\sin x^n$ instead of $\sin^n x$ or even $(\sin x)^n$ is confusing.