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seen Oct 27 at 13:31

Sep
9
awarded  Yearling
Jul
2
awarded  Curious
Apr
28
awarded  Teacher
Apr
28
answered How to prove $\displaystyle\lim_{z\to z_0}\dfrac{f(z)}{g(z)}=\dfrac{f'(z_0)}{g'(z_0)}$
Dec
5
comment Exist a constant $C$ satisfies $\lim_{\varepsilon \to 0^+}\int_{\varepsilon\leq |x|\leq\pi-\varepsilon}|\frac{\sin (n+1/2)x}{\sin x/2}|dx<C?$
@DanielFischer It is a pity... Could you please tell me where do you find this result?
Dec
5
accepted Is $\sum_{n=1}^{\infty}\arctan{\frac{1}{n}}$ finite?
Dec
5
comment Is $\sum_{n=1}^{\infty}\arctan{\frac{1}{n}}$ finite?
Thank you! I get it.
Dec
5
comment Is $\sum_{n=1}^{\infty}\arctan{\frac{1}{n}}$ finite?
Oh... I see! Thanks!
Dec
5
comment Is $\sum_{n=1}^{\infty}\arctan{\frac{1}{n}}$ finite?
I don't get the point... However, (arctan x)'=1/(1+x^2)...... @Pedro Tamaroff
Dec
5
asked Is $\sum_{n=1}^{\infty}\arctan{\frac{1}{n}}$ finite?
Dec
5
asked Exist a constant $C$ satisfies $\lim_{\varepsilon \to 0^+}\int_{\varepsilon\leq |x|\leq\pi-\varepsilon}|\frac{\sin (n+1/2)x}{\sin x/2}|dx<C?$
Dec
5
accepted $\int_0^\pi\int_0^\infty e^{-xy}\sin kx~dy~dx=$ ?
Dec
5
asked $\int_0^\pi\int_0^\infty e^{-xy}\sin kx~dy~dx=$ ?
Dec
4
asked Is it always possible to find a $t>0$, such that $\int_{0}^{t}|\sum_{k=1}^{n}\cos kx|dx<C~~~?$
Dec
3
asked for any $k\in N$, p.v$\int_{a}^{b}\frac{\cos kx}{t-x}dx=?$
Dec
3
comment for any $k\in N$,$\lim_{m\to \infty}\prod_{i=1}^{m}\frac{\sin(\pi k2^{-i})}{\pi k2^{-i}}<\infty?$
Thank you all the same! :)
Dec
3
comment for any $k\in N$,$\lim_{m\to \infty}\prod_{i=1}^{m}\frac{\sin(\pi k2^{-i})}{\pi k2^{-i}}<\infty?$
I also think so. But we need proof, or it's not persuasive.
Dec
3
asked for any $k\in N$,$\lim_{m\to \infty}\prod_{i=1}^{m}\frac{\sin(\pi k2^{-i})}{\pi k2^{-i}}<\infty?$
Dec
3
comment Proving by induction that $1+\frac{1}{2}+\frac{1}{3}+…+\frac{1}{n}\le\frac{n}{2}+1$ holds for all $n \ge 1$
It would be better for showing what B is. :)
Nov
27
comment $\lim_{\varepsilon \to 0}\int_{|x|>\varepsilon}\frac{e^{-(t-x)^2}}{x}dx=?$
could you please tell me which book? I cannot find it.