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location Buenos Aires, Argentina
age 21
visits member for 3 years, 10 months
seen 9 hours ago

(my about me is currently blank)


Oct
14
comment How do we explain to students that division by a vector does not make sense?
It certainly depends on what your multiplication is.
Oct
11
answered Geometric significance of $\sqrt{A^2 + B^2}$ in general equation of line, if any?
Oct
11
revised Geometric significance of $\sqrt{A^2 + B^2}$ in general equation of line, if any?
typo
Oct
9
comment Is there a elementary way to prove $\zeta(2)=\frac{\pi^2}{6}$
The top answer in that post is as elementary as it gets, considering we ate dealing with infinite series. You're not likely to find anything simpler.
Oct
6
comment How to tell if multivariable function is odd?
You just do. It's something you get used to after a while. After all, it's usually pretty easy to tell at a glance whether a function is odd.
Oct
5
comment Let $f,g$ be two distinct functions from $[0,1]$ to $(0, +\infty)$ such that $\int_{0}^{1} g = \int_{0}^{1} f $.
Are those powers or derivatives?
Oct
1
revised Is the function $f(x)= {\sin x \over x}$ uniformly continuous over $\mathbb{R}$?
added 11 characters in body
Oct
1
awarded  Benefactor
Oct
1
accepted Why do we think of a vector as being the same as a differential operator?
Sep
30
comment Why do we think of a vector as being the same as a differential operator?
I think I like your answer the most, but I'll wait a bit longer just in case another one pops up. Thanks!
Sep
29
comment Why do we think of a vector as being the same as a differential operator?
Why is it the only sensible definition? If I have a point $p \in M$ and an open set $U \ni p$ with local coordinates $\phi: U \to \mathbb{R}^n$, then I can choose (for example) the standard basis of $\mathbb{R}^n$, and if I want to use another coordinate system, the vectors transform as dictated by the Jacobian, so my basis is well-defined regardless of the coordinates. Isn't this right?
Sep
28
comment is it true that $\det(I+A)>0$ , if $\det(A)>0$?
+1 This is the simplest example, I think.
Sep
26
comment How to show that the is a $1-1$ correspondence between real numbers and the set of points of a line in the Euclidean plane?
I think the question is about the relationship between $\mathbb{R}$ as a set of numbers and the geometric notion of a line, but I could be wrong.
Sep
26
revised Surprising identities / equations
added 29 characters in body
Sep
26
awarded  Promoter
Sep
25
comment Why do we think of a vector as being the same as a differential operator?
@GeorgesElencwajg: If you think that's the answer, then post it as so. But I still wonder: if there's no reason to make no distinction, why does the author make no distinction?
Sep
23
asked Why do we think of a vector as being the same as a differential operator?
Sep
22
comment Simplify the expression.
Isn't this needlessly complicated? Why not just substract exponents at the second equality, if you're going to do it later anyway?
Sep
21
comment Integrating $\sec^2 x$ from first principles
Why would you not know that? It's not magic, it's very easy to derive.
Sep
21
comment lim calculus problem with infinity
@vilbur: $\frac{n+5-2}{n+5} = \frac{(n+5)-2}{n+5} = \frac{n+5}{n+5} - \frac{2}{n+5} = 1-\frac2{n+5}$.