Reputation
6,746
Top tag
Next privilege 10,000 Rep.
Access moderator tools
Badges
7 27 90
Newest
 Socratic
Impact
~152k people reached

1d
comment Reference Request: Regge Symmetry “Angle-Edge” Duality
I believe Bob Marley is a feasible reference to what you're looking for.
1d
comment How to get rid of the term with $xy$?
One silly doubt: In the book I'm reading, it says about eliminating the linear terms, in another place I've read, it seems that the objective is to eliminate the term with $xy$. Are they equivalent? There is also another book I have that says that the objective seems to be to write the conic in the form $ax^2+bxy+cy^2$. I'm a little confused.
1d
comment How to get rid of the term with $xy$?
I need to do a change of variable such that $xy=0$, right?
1d
comment How to get rid of the term with $xy$?
@r9m What's the difference of them? I know that this matrix form is associated (can be expanded) to a quadratic form. But I'm not sure what your matrix does.
1d
comment How to get rid of the term with $xy$?
@r9m There are two matrixes. This one you mentioned and: $$\begin{pmatrix} {x}&{y}&{1} \end{pmatrix}\begin{pmatrix} {a}&{b/2}&{d/2}\\ {b/2}&{c}&{e/2}\\ {d/2}&{e/2}&{f} \end{pmatrix}\begin{pmatrix} {x}\\ {y}\\ {z} \end{pmatrix}$$
2d
comment Should the expanded expression of a quadratic form be equals to It's original expression?
@RoryDaulton That is also viable. But In my mind, they didn't seem valid for operations in equations. But I jsut checked Apostol's book and saw that they are indeed appropriate. Thanks for pointing it out.
2d
comment What is the $1469^\text{th}$ derivative of $x^{532}-5x^{37}-4$?
@DavidRicherby I know. I just said it to enhance his mathematical culture.
2d
comment Special Products of Transpositions
@Blue You could (should?) have asked it on Math Overflow. As it seems pretty exploratory: "Have these "special permutations" been studied in the literature?" - I guess they'll not close the question.
2d
comment What is the $1469^\text{th}$ derivative of $x^{532}-5x^{37}-4$?
It might be good for you to know the existence of Faá di Bruno's generalization of the chain rule to higher derivatives.
Jul
1
comment When should I shift $a$ and $b$ in $\cfrac{x^2}{a^2}+\cfrac{y^2}{b^2}=1$?
@OfirSchnabel Oh. Then I probably made some mistake in the previous computations. Gonna try it now.
Jul
1
comment Origin of the Integral (Theory Behind It - How it came about)?
I'd suggest you to read Hairer/Wanner's: Analysis by It's History. - It will answer that in much more detail than anyone can present you here.
Jun
30
comment What are some good reasonably rigorous texts on the mathematics of infinity?
@Kyth'Py1k Well, we're here to help. Whenever the need comes, just ask for help. :-)
Jun
28
comment A $X \subseteq \mathbb{A}^n$ such that $I(X) \neq I(V(I(X)))$?
@Surb My friend said that in the context of algebraic geometry, anyone who had studied it would understand.
Jun
28
comment A $X \subseteq \mathbb{A}^n$ such that $I(X) \neq I(V(I(X)))$?
@Surb Notice that the level of this question is far beyond my usual questions. The answer provider even spoke about Hilbert's Nutella. Must be very profound indeed.
Jun
28
comment A $X \subseteq \mathbb{A}^n$ such that $I(X) \neq I(V(I(X)))$?
@Surb This is a question a friend of mine asked me to do: He's a PhD student in a nearby mathematics university but as he had no internet at the moment, he asked me to ask this for him via SMS, as I explained in the comment to the user who provided an answer. My friend told me that no additional motivation was needed and that he had a personal style of asking dry questions.
Jun
28
comment A $X \subseteq \mathbb{A}^n$ such that $I(X) \neq I(V(I(X)))$?
I asked this for a friend: He was having trouble with his internet connection and sent me the question via SMS. As you may have noticed, this is far beyond the level of my habitual questions. He said that your answer is satisfactory and told me to accept it.
Jun
26
comment e and its applications
@user250837 See Courant/John's: Introduction to Calculus and Analysis. Chapter 3, Section 4.
Jun
25
comment Is the focal distance of $x^2+\cfrac{2y^2}{3}=8$ equal to $2\sqrt{-4}$?
@David Yes. For a minute, I made the mistake of thinking that the procedure I made would be obvious.
Jun
25
comment Is the focal distance of $x^2+\cfrac{2y^2}{3}=8$ equal to $2\sqrt{-4}$?
@David Thanks. And sorry for being rude.
Jun
25
comment Is the focal distance of $x^2+\cfrac{2y^2}{3}=8$ equal to $2\sqrt{-4}$?
@anomaly Something poorly written, corrected now.