Calvin Lin
Reputation
33,567
86/100 score
 Mar 31 comment There is a $3\times 3$ orthogonal matrix with all non zero entries.? @PraphullaKoushik The line consisting of vectors of the form $k ( e_1 + A)$ for some constant $k$. Mar 4 awarded Nice Answer Jan 5 revised Prove $n\mid \phi(2^n-1)$ deleted 56 characters in body Jan 5 revised Proving irreducibility of $x^6-72$ added 56 characters in body Jan 5 revised Prove $n\mid \phi(2^n-1)$ added 4 characters in body Dec 29 awarded Yearling Dec 7 revised A tricky probability question. edited body Nov 28 awarded Guru Nov 16 awarded Nice Question Oct 3 answered Inequality. $(a^2+bc)(b^2+ca)(c^2+ab) \geq abc(a+b)(b+c)(c+a)$ Sep 14 revised Minimum of $\frac{1}{x+y}+\frac{1}{x+z}-\frac{1}{x+y+z}$ for $0\leq x+y,y+z,z+x\leq 1$ edited body Sep 12 answered Minimum of $\frac{1}{x+y}+\frac{1}{x+z}-\frac{1}{x+y+z}$ for $0\leq x+y,y+z,z+x\leq 1$ Sep 7 comment How many ways to write $2010$? @joriki Oh haha, yes that works too! You should edit that into your solution, with the cancellation reference. Sep 6 comment How many ways to write $2010$? On the right track at the start, but your cases become complicated. See my solution. Sep 6 comment How many ways to write $2010$? Having found the likelihood of a simplification, it is good to check if there is an actual bijection that we can establish. See my solution. Sep 6 answered How many ways to write $2010$? Sep 6 revised For any arrangment of numbers 1 to 10 in a circle, there will always exist a pair of 3 adjacent numbers in the circle that sum up to 17 or more added 61 characters in body Sep 6 awarded Enlightened Sep 6 awarded Nice Answer Sep 2 answered Functional equation: Show $0\le f(n+1)-f(n)\le 1$ and find all $n$ such that $f(n)=1025$.