Grigory M
Reputation
11,565
366/400 score
 Dec 20 revised Prove that for all non-negative integers $m,n$, $\frac{(2m)!(2n)!}{m!n!(m + n)!}$ is an integer. edited tags; edited tags Dec 20 revised Number of Terms in a Polynomial (4th Degree) edited tags Dec 19 revised Law of sines: uniform proof of Euclidean, spherical & hyperbolic cases more descriptive title; wikipedia ref; minor edits Dec 17 revised Does $\frac{0}{0}$ really equal $1$? edited tags Dec 14 revised Fermat's Challenge added 2 characters in body Jul 24 revised The Name for $\mathbb{R}$, $\mathbb{C}$, $\mathbb{H}$ and $\mathbb{O}$ Exclusively Algebras? edited tags Jul 20 revised Is at least one of $6k + 1$ or $6k-1$ prime? edited tags Jul 18 revised Eilenberg-Maclane space $K(G\rtimes H, 1)$ for a semi-direct product. edited tags Jul 17 revised What does the colon use in the decimal place mean? edited tags Jul 15 revised How to find the length of diagonal of a rhombus rolled back to a previous revision Jul 14 revised If each each of two natural numbers $a$ and $b$ is a sum of two squares then $ab$ is also a sum of two squares more descriptive title Jun 15 revised Gauss-type sums for cube roots One concrete positive result added (+a typo fixed) Jun 2 revised CHECK: Let p be a prime number. Show that $\binom{2p}{p}$ is congruent to $2$ mod $p$. edited tags May 26 revised Spin manifold and the second Stiefel-Whitney class texified May 23 revised Let $a,m,n \in \mathbf{N}$. Show that if $\gcd(m,n)=1$, then $\gcd(a,mn)=\gcd(a,m)\cdot\gcd(a,n)$. edited tags May 23 revised Find all integers $n$ (positive, negative, and zero) so that $n^2 + 1$ is divisible by $n + 1$. edited tags May 21 revised Direct proof that for a prime $p$ if $p\equiv 1 \bmod 4$ then $l(\sqrt{p})$ is odd. edited tags May 21 revised Open covers by simply connected sets and fundamental group more descriptive title May 20 revised Fibonacci combinatorial identity edited tags May 20 revised Finding integral solutions to the equation $x^4-ax^3-bx^2-cx-d=0$ edited title