# qoqosz

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bio website qoqosz.net location Poland age 26 member for 2 years, 8 months seen 19 hours ago profile views 299

I'm just a physics student.

# 164 Actions

 Dec7 awarded Enlightened Dec7 awarded Nice Answer Oct27 awarded Popular Question Sep30 awarded Explainer Sep20 awarded Necromancer Jul23 awarded Good Answer Jul2 awarded Curious May17 awarded Yearling Feb16 answered Definite integral involving arctan and tan Nov6 comment A closed form for the sum $\sum_{n=1}^{\infty}\left(\frac{H_n}{n}\right)^2$ Nov6 comment Integral $\int_{-\infty}^{\infty}\frac{\mathrm dx}{(ax^2+2bx+c)^{\alpha}}$ It's one of the Beta function (en.wikipedia.org/wiki/Beta_function) representations. If you substitute $p = u^2$ it will become more apparent. Nov5 revised Evaluating $\lim\limits_{n \to \infty} (\int _a^b|f(x)|^ndx)^\frac 1n=\max\limits_{x\in[a,b]}|f(x)|$ added 17 characters in body Nov5 comment evaluation of $\int\frac{x^2}{\left(1+x^4\right)\sqrt{1+x^4}}dx$ If you are looking for an elementary solution - there isn't one due to: encyclopediaofmath.org/index.php/… Nov5 comment Integral from zero to infinity of $\int_0^{\infty}\frac{(1-e^{-\lambda z})}{\lambda^{a+1}} d \lambda$ @ghiasi This condition appears when you check when $\int_0^z t^{a-1} dt$ and $\int_0^{+\infty} x^{-a} e^{-x} dx$ converge ($z > 0$). Nov4 answered Evaluating $\lim\limits_{n \to \infty} (\int _a^b|f(x)|^ndx)^\frac 1n=\max\limits_{x\in[a,b]}|f(x)|$ Nov4 answered Integral from zero to infinity of $\int_0^{\infty}\frac{(1-e^{-\lambda z})}{\lambda^{a+1}} d \lambda$ Nov4 answered Show that if $x>0$, then $\ln(x)\geq 1-\frac{1}{x}$ Nov2 comment Integration in n-spherical coordinates Thanks, I've already got an answer on physics.SE: physics.stackexchange.com/questions/83103/… Oct31 asked Integration in n-spherical coordinates Oct13 comment Divergence in spherical coordinates @user8268 So if $\vec F$ is defined as: $F^\alpha = \frac{\partial f (u(r, \theta, \phi), \ldots)}{\partial (\nabla_\alpha u)}$ and I compute $\nabla_\alpha u$ as $(\partial_r u, \frac{1}{r} \partial_\theta u, \frac{1}{r \sin \theta} \partial_\phi u)$ than which formula for $\nabla \cdot \vec{F}$ should I use? The first one?
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