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1h
awarded  Disciplined
3h
comment How to conclude from here that $f$ is a constant function or not?
Are $k$ and $n$ arbitrary in $\mathbb N$ ?
3h
comment How to conclude from here that $f$ is a constant function or not?
Previous question at math.stackexchange.com/q/1038492.
3h
revised Relating convergence theorem for Newton-Raphson method to Newton fractal
added 317 characters in body
3h
comment Relating convergence theorem for Newton-Raphson method to Newton fractal
See also math.stackexchange.com/q/34581.
4h
comment How to conclude from here that $f$ is a constant function or not?
@learnmore, ask a separate question.
4h
answered How to conclude from here that $f$ is a constant function or not?
4h
answered Relating convergence theorem for Newton-Raphson method to Newton fractal
4h
revised Each element is a square of some element
added 15 characters in body
4h
comment Each element is a square of some element
@MaryStar, $y=-y$ in characteristic $2$ and so $x+y=x-y$.
6h
answered Each element is a square of some element
6h
comment Suppose that $[G:H]$ is a prime integer, and that $g \notin H$. Prove that H is normal in G.
It seems to me that the question is: if every left coset of $H$ is a right coset and if the index is prime, then $H$ is normal.
7h
comment Automorphisms of the field of real numbers
See math.stackexchange.com/q/449404 and math.stackexchange.com/q/369481.
10h
comment Let $A_{j,k} = \langle x_j, x_k\rangle$. Show $A$ is invertible if and only if $x_1, \ldots, x_n$ are linearly independent.
Of course it is.
10h
comment Let $A_{j,k} = \langle x_j, x_k\rangle$. Show $A$ is invertible if and only if $x_1, \ldots, x_n$ are linearly independent.
That'll work, and was my first thought, but using the correct coordinates works as well and is simpler.
10h
comment Let $A_{j,k} = \langle x_j, x_k\rangle$. Show $A$ is invertible if and only if $x_1, \ldots, x_n$ are linearly independent.
Since the inner product is not necessarily the standard one, $x_{ij}$ need to be coordinates with respect to an orthonormal basis for that inner product.
10h
comment difference between theorem, lemma and corollary
See also en.wikipedia.org/wiki/List_of_lemmas for a list of famous lemmas.
10h
answered Sensitivity of polynomial global minimizers with respect to perturbations in the coefficients.
11h
comment Proof or counterexample: If $F\subseteq K$ and $r\in K$. If $[F(r):F]=4$ then $F(r)=F(r^3)$.
It should be $x^6$ instead of $x^5$.
11h
comment What is the size of the opening of a parabola?
See en.wikipedia.org/wiki/….