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


Oct
8
comment How do I take the limit of this function?
You must be doing something wrong: when I put in $2.1$, $2.01$, $2.001$, I get $15$, $150$, $1500$, etc.
Jun
16
comment Using dimensional analysis to evaluate $\frac{d}{dx}x^n$
@tpb261: I feel like the issue here, this being a man site and all, is showing that you can't make a non-constant dimensionless function out of only $ x $. For all we know, there might be a constant $ a $ with dimensions of length such that $ c =x/a $.
Jun
16
comment I can't quite figure out this “separable equation”
Small correction: having $\ln x$ in the equation already tells us that $x \neq 0$. Instead, you should assume that $x \neq 1$ so $\ln x \neq 0$.
Jun
16
comment Using dimensional analysis to evaluate $\frac{d}{dx}x^n$
I'm wondering if this would be a better fit at Physics, or if they would tell you that it's obviously correct.
Jun
7
comment How to explain the perpendicularity of two lines to a High School student?
The question is about how to explain the fact that the product of the slopes is $-1$.
Jun
7
comment How to explain the perpendicularity of two lines to a High School student?
I think you should read the question a little more. A high school student doesn't need real life examples to understand what "perpendicular" is.
Apr
27
comment Have you encountered this integral?
I think you mean $P$ is the transform of $f$.
Apr
23
comment Taylor expansion of a not easily differentiable function
@Fred: Taylor series around where? The function doesn't work for $ x\le 1$, that's the problem.
Apr
13
comment Difficult Improper Integral
What's so terrible about $\frac{114}{19}$?
Feb
6
comment For which constants does the following converge to a delta function?
Depending on your definition of a delta function this may not be possible, since the integral of your function over $\mathbb{R}^2$ doesn't converge for any $n$, no matter what $c_n$ is. As far as I know, the delta function must verify $\int_\mathbb{R} \delta(x)\ dx = 1$.
Feb
5
comment Evaluating $\int \frac{1}{\sqrt{x^2 + a^2}}\, dx$ without resorting to trigonometric $u$-substitution
Would you accept hyperbolic functions? :)
Jan
1
comment Is this a solution to the indefinite integral of $e^{-x^2}$?
This is a nice idea, but I'm sorry to tell you that there's proof that there is no elementary formula for the integral. If you're okay with a series, just expand $ e^{-x^2} $ and integrate term by term.
Dec
13
comment Can integration get the real value of $\pi$?
@user3015600: You could, in principle, get $\pi$ with infinite precision. If you want any digit of the decimal expansion of $\pi$, there's a zillion formulas that you can use to get it. The problem is that we can never know all of them, not because math doesn't work, but simply because there's infinitely many of them and we don't have infinite time.
Dec
10
comment Explain complex numbers
Also, I think this is a duplicate: math.stackexchange.com/questions/251665/…
Dec
10
comment Explain complex numbers
@tandberg: You can't always explain something at a level the other person can understand. If your cousin is familiar with the plane and a bit of analytic geometry, you can make the connection there. Otherwise, I'm not sure.
Nov
25
comment $2\times2$ matrices are not big enough
@MarcvanLeeuwen: The reason I made my comment is that yours seemed to imply that this isn't a very good example because it's not evident how to define a rotation matrix for $n > 2$ dimensions. I just wanted to make clear that $3$-dimensional rotation matrices are easy to define and don't commute, that's all.
Nov
24
comment $2\times2$ matrices are not big enough
@MarcvanLeeuwen: Rotation matrices don't commute in three dimensions.
Nov
15
comment Solving $y'' + (ax+b)y = 0$
Side note; how do I make the expression for $\phi(k)$ look nice? The symbols look extremely small to me.
Oct
29
comment can not find the proof that logarithms are the inverse of exponentials
What's your definition of both? People usually define one of those to be the inverse of the other.
Oct
28
comment What situations/models require calculating the area under a curve?
Are you asking specifically about finding the area below a curve, or about integrating in general? Because there is an endless list of uses for the latter.