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 1d comment Don't know how to approach $x \cos(x) - 2 \cos^2(x) = 2$ $5.2008013281450192338$ is not recognized by the ISC isc.carma.newcastle.edu.au 1d revised Don't know how to approach $x \cos(x) - 2 \cos^2(x) = 2$ misprint 1d comment Analytic continuation of a real function @JohnFernley ... That is the "identity theorem" mentioned before. If two analytic funtions defined on a connected domain agree on a set with a limit point (for example, the real line is such a set), then they agree on the whole domain. 1d awarded Revival 1d comment How to find the radius of convergence of $\sum_{n=0}^{\infty}[2^{n}z^{n!}]$ What you computed is the radius of convergence for $\sum 2^n z^n$. For radius of convergence of $\sum 2^n z^{n!}$ you should use the $n!$ order root of $2^n$. 2d answered Analytic continuation of a real function 2d comment Analytic continuation of a real function @YoTengoUnLCD ... Uniqueness of the extension (if it exists) is the identity theorem. But he is asking about existence of the extension. 2d comment Expressing integral of u^v in terms of integral of u and v See the similar question on integral of a product: math.stackexchange.com/questions/50671 2d answered Expressing integral of u^v in terms of integral of u and v 2d comment Why does the harmonic series diverge but the p-harmonic series converge So, first understand intuitively whey $\int_1^\infty dx/x$ diverges but $\int_1^\infty dx/x^2$ converges. Then it should not be so surprising that the same thing is true for series. Apr 27 comment bessel function integration He said $P=1$ so I left out that factor. I also put in what he said $J$ is. Apr 26 answered Real problems solved with systems Apr 26 comment Metric space of non empty closed bounded parts of $R$ with the Hausdorff metric For a mathematically correct way, you might guess what the limit is, then use the $\epsilon$ type definition to prove convergence to it. Apr 26 comment Derivative of a self-referencing function Your calculus textbook should have a section on "implicit differentiation". Apr 26 comment Is $\omega-1$ finite? Next you can try $\omega/2$ or $\sqrt{\omega}$ or $\omega^{1/\omega}$. All meaningless in the ordinals. But investigate the surreal numbers. Apr 25 revised Solution of $x^2e^x = y$ added 58 characters in body Apr 25 answered Solution of $x^2e^x = y$ Apr 25 comment Show that the sum $\sum_{k = 0}^n 2^k \binom{n}{k}$ is equal to $3^n$ T. Bongers means "binomial theorem". Maybe Fourier wants a combinatorial interpretation. Apr 25 comment Finite Integral involving Bessel Function, $J_1$ For even $n$, you can get the integral $\int x J_n(x)\;dx$ not using Struve. Apr 25 awarded Nice Answer