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Sep
30
awarded  Explainer
Jun
3
awarded  Yearling
Jun
1
comment Terminology: Name for general, non-differential equations over $\mathbb{R}^n$
@PatrickDaSilva: en.wikipedia.org/wiki/Closed-form_expression
Jun
1
comment Terminology: Name for general, non-differential equations over $\mathbb{R}^n$
What do you mean by a function $f:\mathbb{R}^n \to \mathbb{R}$ being a closed form expression. It's obvious when $n=1$, but for $n>1$ it is unclear imho.
May
25
comment Is this predicate logic true?
$\infty$ is not a real number. Saying "It's $\infty$" is not accurate.
May
24
revised Find eigenvector of the linear operator
added 1090 characters in body
May
24
answered Find eigenvector of the linear operator
May
22
revised Subfields of $\mathbb{Q}$
explained how to get the inverses
May
22
suggested approved edit on Subfields of $\mathbb{Q}$
May
22
answered Two functions discontinuous, but sum continuous
May
20
answered This limit supposed to be $0$ but I get $2$, why?
May
9
comment Extending the Intersection of Subspace
okay deleting my answer since the original poster is more interested in the small dimensional cases. Can you post the counter example if you're still interested in this problem.
May
9
comment Extending the Intersection of Subspace
Your dimensional identity is incorrect. $\dim (U_1+U_2)=\dim U_1+\dim U_2 - \dim(U_1 \cap U_2)$
May
6
comment When is a ring homomorphism also a R-module homomorphism?
Very nice. It might be worth pointing out that the image $Im(\varphi)$ is an ideal (usually it's just a subring) and it's not a matter of $R$ being full of zero divisors but rather $Im(\varphi)$ must consist entirely of zero divisors if $\varphi \neq id$.
May
6
comment Applications of simultaneous diagonalization of quadratic forms
I don't think it's diagonalization unless $S^T=S^{-1}$
May
6
answered Absolute values don't work
May
5
comment Applications of simultaneous diagonalization of quadratic forms
What else do you know about S? Is it orthogonal by chance?
May
5
answered Solving two varibles system equation above $\mathbb{C}$
May
3
revised Suppose that $F : X \longrightarrow Y$ is a function and $A$, $B$ are subsets of $Y$. Prove or disprove the following:
edited in math
May
3
suggested approved edit on Suppose that $F : X \longrightarrow Y$ is a function and $A$, $B$ are subsets of $Y$. Prove or disprove the following: