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6m
comment Old and recent results concerning the number of real roots for a polynomial function
$\le n$ (if $a_n\ne 0$) is a fairly old result ...
10m
comment Proving that $\cos(2\pi/n)$ is algebraic
This uses the fact that the set of algebaics is closed under addition (and division by two). This is maybe too much §of the properties of the field of algebraic numbers (specifically thatit is a flied)"
15m
comment Definitions of $\mathrm{Hom}(V,W)$
There should not be an equal sign between the set of linear maps and the set of matrices; these spaces are merely isomorphic
12h
revised How to prove the elementary inequality?
added 644 characters in body
21h
comment How to prove a point in a set is an extreme point of the set ?
It suffices that there exists a line $\ell$ with $x\in \ell$ such that $x$ is an extreme point in $\ell\cap K$ (i.e., $x$ is one endpoint of the interval)
21h
comment Divisor of a finite group
"Note that the set of tuples with some entries distinct is a disjoint union of orbits each of which consists of d tuples" - Doesn't thsi assume that $d$ is prime?
21h
answered I have really solved the problem of how to trisect the plane anglel
1d
answered How to prove the elementary inequality?
1d
comment Rules for multiplying exponents by scalars
The abilty to do so is more or less the definition of "$=$"
1d
answered Understanding terminology related to implementing the sobel edge detection algorithm
1d
comment Check if a point is inside a rectangle (not knowing the coordinates, but knowing distances to vertices)
Do you at least know the side lengths of the rectangle?
1d
comment Non-Empty Finite Subset $U$ of $\mathbb{R}$ is not Open
Yes, that's fine. It would be enough to state that specifically $x-\frac12\delta\notin U$ with $x=\min U$.
1d
answered What are the facts used in each step of this proof?
1d
comment What are the facts used in each step of this proof?
I'd even suppose $=$ instead of $\le$ in that place
1d
answered Is there a finite abelian group $G$ such that $\textrm{Aut}(G)$ is abelian but $G$ is not cyclic?
1d
comment for which values of $\theta$ does this equation $x^{\cos\theta} +y^{\sin\theta }=1$ have solutions in integers .?
If $\cos\theta> 0$ and $\sin\theta\ge 0$ then $x=0$, $y=1$ is a solution. If $\cos \theta= 0$ and $\sin\theta=1$, then $x=1$, $y=0$ is a solution. There is clearly no solution with exponents $-1$ and $0$. Remains the case of noninteger exponents, at least one negative.
1d
answered Where can I find a proof of this result?
1d
answered Understanding part of a proof of l'Hôpital's Rule
1d
comment Natural action of $S_n$ on $\{ 1,2,\dots,n \}$
@sandstone it is equivalent because the existence of $g$ with $gx=y$ is equivalent to $x,y$ being in the same orbit.
2d
answered Is the intersection of two locally compact locally compact?