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seen Apr 16 at 9:19

Apr
16
comment Subgroups of finite Abelian groups
For your first question: Take B_i to be the p_i sylow subgroup of B, then it is contained in the unique p_i subgroup of A as it is a p_i-group.
Apr
5
answered Subgroups of finite Abelian groups
Apr
4
answered A Corollary from Burton's Elementary number theory
Mar
11
awarded  Yearling
Mar
7
revised How many topologies can be defined on a finite set with $n$ element?
fixed some typos
Mar
7
suggested suggested edit on How many topologies can be defined on a finite set with $n$ element?
Jan
28
comment Finding $ \lim_{x \to 0^+} (\frac{\arctan (x)}{x})^{\frac{1}{x^2}} $ without power series.
Isn't $\lim_{x\to 0} \frac{\log(1+x)}{x}=1$ is the definition of the derivative of $log(1+x)$ at $x=0$? It's a bit weird to prove it using L'hopital that uses the derivative of $\log(1+x)$, no?
Dec
14
awarded  Popular Question
Jul
31
comment How many solutions modulo prime?
If $k=0$ and $p>2$, there are $p(p-1)$ coming from $x=y$ and $x=-y$.
Apr
22
comment Subsequence that converges
P.. wants to generate a subsequence of $x_n$ that tends to $L$. A criterion for that is that for every $\epsilon>0$ there is an infinite number of indices $k$ such that $x_{k}\in (L-\epsilon,L+\epsilon)$.
Apr
22
comment Subsequence that converges
There's a minor detail missing: You need that the set of $k$'s chosen to be infinite. (In the event of $L_n=L$ and $x_k=L$, you proof may give only one $k$...)
Apr
22
comment Prove or Disprove the following: If $K$ is a maximal subgroup that is normal, in $G$ then $G \cong K \times_{\theta}H$
It is not clear to me what is exactly the question...
Apr
22
comment $R = \{(f,g) \mid f(0) = g(0)\;\text{or}\; f(1) = g(1)\}$ The relation is…
I consider several examples of pairs $(f,g)$ that satisfy the relation to get a feeling what it is, and to check, at least in these examples, the properties. For example look at the pairs: $f_1(n)=n$ and $g_1(n) = -n$; $f_2(n) = n$ and $g_2(n) = 2n-1$; $f_3(n)=n+10$ and $g_3(n) = 11n$.
Apr
22
comment How do I determine if given set is a subspace of the specified vector space (answer provided)?
I think what you need to prove is that, when $a,b,c$ run over all triplets of reals, the set you get is closed under sums and under multiplication by scalars.
Apr
17
comment Transformation $T:V \to W$ such that $N\subset \text{Null}(T)$
So for what are you looking?
Apr
2
comment Prove that similar matrices have the same geometric multiplicity
@GitGud any $P$ that do not commute with $A$, I guess...
Apr
2
answered Prove that similar matrices have the same geometric multiplicity
Mar
28
comment Why do we negate the imaginary part when conjugating?
very nice answer!
Mar
28
answered How do we know the rank is 1?
Mar
28
comment Proving $\gcd(n^2(n^2+1),2n+1)=\gcd(2n+1,5)$
Since $n^2$ and $2n+1$ are coprime, the $n^2$ on the lhs can be dropped.