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Nov
19
accepted What is the meaning of primes here?
Nov
19
comment What is the meaning of primes here?
Oh, in Portuguese, they call it "linha' (line). I always thought it would be "x line" in English.
Nov
19
asked What is the meaning of primes here?
Nov
13
revised Archimedean integration of $x^3$?
deleted 174 characters in body
Nov
13
revised Archimedean integration of $x^3$?
added 2 characters in body
Nov
13
comment Archimedean integration of $x^3$?
@Peter Yes. A typo. I'll correct it. And I guess it's cheating because Archimedes didn't have exactly the notion of a limit. Besides, Apostol doesn't use it.
Nov
12
asked Archimedean integration of $x^3$?
Nov
11
awarded  Famous Question
Nov
5
accepted Find the points on the ellipse $x^2+2y^2=1$ where the tangent line has slope $1$.
Nov
5
asked Find the points on the ellipse $x^2+2y^2=1$ where the tangent line has slope $1$.
Oct
20
awarded  Popular Question
Oct
17
awarded  Popular Question
Oct
12
comment Is my proof of $-(-a)=a$ correct?
Is it too problematic to work on a representation? I wrote some ideas on a paper that was intended to teach mathematics. My goal was to bring up the idea of equivalent rewritings, loosely based on this. So these naive rewritings became my media for doing proofs in mathematics and for the first time I had a deeper access to mathematics. I guess I was following something like the formalist school.
Oct
12
accepted Is my proof of $-(-a)=a$ correct?
Oct
12
comment Is my proof of $-(-a)=a$ correct?
I don't get it. Suppose the scenario you proposed: $a+A=0$. How would you do from here?
Oct
12
comment Is my proof of $-(-a)=a$ correct?
Good point. I'll think about it.
Oct
12
comment Is my proof of $-(-a)=a$ correct?
You mean theorem 1.2?
Oct
12
comment Is my proof of $-(-a)=a$ correct?
If I have $a$ and it's inverse is $-a$, then It seems natural to expect the inverse of $-a$ to be $-(-a)$. That's what I meant with "packing with a minus sign".
Oct
12
revised Is my proof of $-(-a)=a$ correct?
rolled back to a previous revision
Oct
12
asked Is my proof of $-(-a)=a$ correct?