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2d
answered What is the relation between $a$ and $b$?
2d
comment What is the relation between $a$ and $b$?
$p$ divides $a$ if and only if $p$ divides $b$ - there is nothing more to say, I wouldn't call this a "relation"
Oct
24
answered Why does 2^-2 equal 1/2^2?
Oct
21
answered Question about the wording of a Ring Theory problem involving ideals
Oct
20
comment Proof that $\sum\limits_{i=1}^n \cos \sqrt{i}$ is unbounded.
first idea:$$ \cos \sqrt{n} = 1 - {n \over 2} + {n ^2 \over 4!} -\dots $$
Oct
17
comment Question about the Characteristic of $\mathbb{F}_{p^n}$
For any Ring $R$ there is a Homomorphism $\mathbb Z \rightarrow R$, which cannot be injective if $R$ is finite. If $R$ is a domain, then the kernel must be a prime ideal $(p)$.
Oct
16
comment Gelfand trigonometry question
Sorry, I was totally wrong. I thought for a moment that $c^6+s^6=1$...
Oct
16
answered Question about the Characteristic of $\mathbb{F}_{p^n}$
Oct
16
revised Gelfand trigonometry question
added 413 characters in body
Oct
15
answered Gelfand trigonometry question
Oct
13
answered Justify: $R$ is commutative
Oct
10
comment Value of $c$ for which Continuity holds in $\mathbb R^2$.
take the sequences $({n-1\over n},0)$ and $({n+1\over n},0)$
Oct
10
answered A simple module
Oct
9
comment $|G|=p^3$. Prove that $\phi(x)=x^p$ is a homomorphism
the center $Z=Z(G)$ is a nontrivial normal subgroup (we assume it is $\neq G$). so let $x,y \notin Z$ and let $$ 1 \neq c := xyx^{-1}y^{-1} \Rightarrow xy=cyx $$ Show that $c\in Z$ and multiply by $x$ and iterate to get formulas for $x^ny$ and $x^ny^n$
Oct
7
answered The set of subsets of size $k$ in $\mathbb{N}$ is countable
Oct
6
answered Subset of a Cartesian product?
Oct
1
comment prove that a set is non empty
And in that case $1$ is in the set, so the assertion is true. I guess they have to show that for every $q < a$ there are only finitely many $d(k)$ less then $q$
Sep
30
answered Problem with a solution to the integral $\int_{-\infty}^{+\infty}e^{-x^2}\mathrm{dx}$
Sep
30
revised invertible matrix and upper triangular matrix
added 17 characters in body
Sep
30
answered Cauchy's Inequality $|f(z)|\leq k|z|^2$