1h
answered What do mathematicians call a proof?
1h
comment Evaluation of $ \int_{-\infty}^{\infty}\arctan (\frac 1{2x^2})\ \mathrm dx$
I think it is unreasonable to expect a connection. Integral $\int_1^\infty (1/x^3)\,dx=1/2$ but I doubt that helps in evaluating $\sum_{n=1}^\infty 1/n^3 = \zeta(3)$.
1h
comment Evaluation of $ \int_{-\infty}^{\infty}\arctan (\frac 1{2x^2})\ \mathrm dx$
Why do you think the integral is related to the sums?
1h
comment Ignore this question no more
closed after less than a minute!
13h
comment Branch cut of $\sqrt{z}$
Your notation here is a bit off. Try to come up with a situation where your proposal would be useful.
13h
comment What makes it legitimate to multiply both sides?
Your "operation" is a "function". And functions have this property (the "vertical line property"): if $x_1=x_2$, then $f(x_1)=f(x_2)$.
1d
comment When/How were the product and chain rules first proved?
Wasn't there some early work where it was assumed that the derivative of the product is the product of the derivatives?
1d
comment Find all functions f such that $f(f(x))=f(x)+x$
OK, how to prove surjective in the decreasing case?
1d
comment What does it exactly mean to be sharp?
In the context of music? "The oboes are sharp!" (It means they are off-key, a bit too high-pitched.) When you ask a question here, first look in a dictionary, and report your results with your question.
1d
revised Find all functions f such that $f(f(x))=f(x)+x$
added 25 characters in body
1d
revised Find all functions f such that $f(f(x))=f(x)+x$
added 206 characters in body
1d
answered Find all functions f such that $f(f(x))=f(x)+x$
2d
awarded Nice Answer
2d
comment Are women physically weaker?
So, should we argue against separate men's and women's races in the Olympics?
2d
answered Is there anything wrong with this proposed proof of the irrationality of Euler's constant?
2d
comment Does "$\dots$" imply countability?
You can probably find things like: consider the set of real numbers $0, \cdots, 1$.
2d
answered Solving the integral $\int_{-\infty}^{\infty} (1+x^2)^{-3/2}$ with $\sinh$, $\cosh$?
2d
comment I am trying to find where $\sin ( \pi t) e ^{ -t } $ converges via secant method and I keep getting this error below with my code.
You mean this is not the place to come for free code debugging?
2d
comment Differential algebra and differential-algebraic equations
Differential algebra uses an algebraic structure that has not only the usuall operations, but also a "derivative" operation. (Or even more than one.) So it will model a situation where you have a space of $C^\infty$ functions with the usual operations of addition, multiplication, and differentiation. One common topic is something like Galois theory, where you want to study whether solution of a DE is possible in terms of certain simpler solutions (such as quadratures, or elementary functions).
Aug
27
comment How do you say "plan documentaire" in english
If , in fact, it means "list of documents", then why not use the translation "list of documents"?
1 2 3 4 5