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 Apr14 accepted ODE arising in physics Apr14 revised ODE arising in physics added 69 characters in body Apr14 revised ODE arising in physics added 2 characters in body Apr14 revised ODE arising in physics deleted 2 characters in body Apr14 comment ODE arising in physics @CameronWilliams WA's answer should be correct, but it is not enlightening at all. I would appreciate learning about the process of how to solve it :) Apr14 asked ODE arising in physics Apr11 comment limit of sequence of quotients of sequence that converges @user3697301 Intuitively, it is correct because it would grow faster than an unbounded geometrical summation. Can you continue? Apr11 answered Volume of a region? Apr9 comment $\lim_{(x,y)\to (0,0)}\frac{\sin^3x}{x^2+y^2}$ $y$ wasn't ever necessary, not even polar coordinates :) $$0 \leq \left|\frac{\sin^3{x}}{x^2+y^2}\right| \leq \frac{|x|^3}{x^2+y^2} \leq \frac{|x|^3}{x^2}$$ Apr1 comment How to evaluate $\left(\cos{\frac{5\pi}{9}}\right)^{11}+\left(\cos{\frac{7\pi}{9}}\right)^{11}+\left(\cos{\frac{11\pi}{9}}\right)^{11}$ @JyrkiLahtonen That's true... Apr1 comment How to evaluate $\left(\cos{\frac{5\pi}{9}}\right)^{11}+\left(\cos{\frac{7\pi}{9}}\right)^{11}+\left(\cos{\frac{11\pi}{9}}\right)^{11}$ Say your each term(without the exponent) is $x,y,z$. Then $x,y,z$ are the three solutions of $\cos\alpha$ in $$1/2=\cos3\alpha=4\cos^3\alpha-3\cos\alpha$$ Mar28 comment is it possible to find $x$ where $y$ is equal to a whole number in a non iterative fashion Any solution to this problem(with arbitrary coefficients) would solve an arbitrary factoring with the same complexity. You can trivially test all divisors in $O(\sqrt{d})$ time. How huge are those numbers going to be? Mar25 comment Find the smallest postive integer $n$ such \$H(n)