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 May 25 comment Evaluating a double integral @Dostre I doubt it - you say you want to integrate $\int_x^x f(x)dx$, or something similar. May 24 comment Good Physical Demonstrations of Abstract Mathematics Perhaps it is continuous from the Navier-Stokes perspective? May 24 comment What is a Number Theorist Then feel free to try some of the answers - but I think you're grossly missing the point in that case. Standard high school education doesn't teach you real mathematics. May 23 comment What is a Number Theorist Thanks - I notice that many math friends mistake the general public for understanding what it is that mathematicians do. May 23 comment How to show that $\frac{\pi}{5}\leq\int_0^1 x^x\,dx\leq\frac{\pi}{4}$ Aha! But the question is not to evaluate the integral explicitly, which indeed is impossible in standard functions, but to prove the inequality, which I admit is pretty hard too, but not impossible. May 20 comment Convergence of series based on convergence of sequence More precisely, the $C_i$ depend on $n$. May 20 comment Convergence of series based on convergence of sequence That's a recursive argument - what's $C_i$? May 20 comment Convergence of series based on convergence of sequence I'd like a more formal proof - how do I pick $N$ such that $|\sum_{i=0}^n q^i t_{n-i}|<\epsilon$ for all $n\geq N$? May 20 comment Convergence of series based on convergence of sequence Okay, so what is a suitable large $n$? May 20 comment Convergence of series based on convergence of sequence @Phira: please illustrate - I have tried that approach to no avail. May 20 comment Convergence of series based on convergence of sequence Oops, I forgot to add the $\lim$. See edit. @Brett: like how? Apr 28 comment Evaluating $\int_a^{\infty} x e^{-(x-a)} dx$ Great. So now what? Apr 23 comment Undergrad Student Trying to Figure Out What to Study Wait, is this as vague as I think it is? :P That said, you should probably pursue what you're good at, because that's usually an indicator you like doing it. Apr 19 comment Integral metric. Isn't this exactly how we construct a Hilber space? Apr 19 comment Solutions to $x_1+2x_2+3x_3+4x_4+5x_5+6x_6+7x_7+8x_8+9x_9+10x_{10}\equiv0\mod11$ You did not read the question quite carefully. Apr 18 comment Maximum of an entire function Yes, your theorem is true. This is a proof by contradiction. Apr 17 comment rotating a matrix XKCD may be helpful in solving this question. xkcd.com/184 Apr 17 comment Is there a way to tell whether a paper has been rigorously peer-reviewed and is completely valid? If it's in an important magazine, other professionals have had a look, so you can be fairly sure years of study won't help reliability. Apr 17 comment Integral equation solution hint. Necessarily, $\lim_{x\to\infty}f(x)=0$, if that helps. Apr 17 comment Show that for a finite metric space A, every subset is open Viewing problems in a more general light can sometimes help. In this case, an abstract question (about open and closed sets) is asked, and I clarified it by the more intuitive understanding of discrete spaces. And apparently the question owner was helped.