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location Buenos Aires, Argentina
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(my about me is currently blank)


Oct
15
comment What's the integral of $\frac{-4x}{1+2x}$?
Constants don't matter when doing integrals. In this case, the $-1$ gets absorbed into the $+C$ that you should have put when doing the integral.
Oct
14
answered Integration by parts: $\int xe^{-x}dx$
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?