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location Buenos Aires, Argentina
age 21
visits member for 4 years, 1 month
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(my about me is currently blank)


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: $\frac{n+5-2}{n+5} = \frac{(n+5)-2}{n+5} = \frac{n+5}{n+5} - \frac{2}{n+5} = 1-\frac2{n+5}$.
Sep
21
comment lim calculus problem with infinity
Also, the nth-root of n goes to $1$. If you don't believe me, take the logarithm of the expression.
Sep
21
comment lim calculus problem with infinity
The fraction goes to $1$ but the exponent goes to $\infty$; this doesn't go to $1$ but rather is an indeterminate case, as evidenced by the well known fact that $(1+\frac1{n})^n \to e$.
Sep
20
answered lim calculus problem with infinity
Sep
20
revised lim calculus problem with infinity
added 25 characters in body
Sep
18
comment Does infinite time = time with no end = never?
The short answer is that if it takes an infinite amount of time to reach point B, then the object never reaches it. Of course, in the real world, no matter how precise your measurement is, there will be some time after which the object is closer to B than your instrument can distinguish.
Sep
17
awarded  Popular Question
Sep
17
reviewed Reject suggested edit on Property of $W_0^{1,p}(\Omega)$
Sep
16
answered Solving one-sided limits analytically
Sep
10
comment Infinite amount of additions, finite sum?
@ZoltánSchmidt: While I found your question interesting, I think at some point you just need to accept that adding an infinite amount of terms can result in a finite result, and the intuition will come later. Someone on this site once quoted something along the lines of "In math, we don't understand things; we just get used to them". Try to work out the $\sum \frac1{2^n}$ example. It's easy to do and it will give you some insight as to why the total sum is $2$ and not $\infty$.