Emanuele Paolini
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 Nov20 answered Proof $x=\sin(x+1)$ has one solution in $\mathbb{R}$ Nov18 comment Rolling ellipse on line - tangent and normal of roulette $F$ and $K$ are fixed on the ellipse, so their distance is fixed. At time $t$ it happens that $K(t)$ is on the line, at other times the tangent point will be different. Nov18 answered Studying the differentiability of a function at a point $(a_{1},a_{2})$ Nov18 answered Proving the convergence/divergence of a seemingly oscillating series Nov18 answered Rolling ellipse on line - tangent and normal of roulette Nov18 comment Rolling ellipse on line - tangent and normal of roulette $K$ is the center of the "infinitesimal rotation" of the point $F$. So the velocity of $F$ is perpendicular to $FK$. Nov17 comment Prove or disprove: functions Maybe $X'$ is the complementary set of $X$? Nov11 revised About Banach Spaces And Absolute Convergence Of Series typo Nov11 comment Limit of derivatives and continuous $\lim_{x\to 1^-} f'(x) = \lim_{x\to 1^-} \frac{1}{(1-x)^2} = +\infty$, it exists even if it is not finite. Nov7 comment Limit of derivatives and continuous But, again, this is true only if the limit of $f'$ exists and it is finite. Nov7 comment Limit of derivatives and continuous It is possible that the limit of $f$ is infinite and the limit of $f'$ exists. Take $f(x) = 1/(1-x)$. Nov7 revised Limit of derivatives and continuous deleted 1 character in body Nov7 comment Limit of derivatives and continuous It is correct if you take $h(x) = g(1/2) + \int_{1/2}^x g'(t)dt$ (check the sign). Nov7 comment Limit of derivatives and continuous Continuity of a function tells nothing in the points outside the domain. Nov7 answered Limit of derivatives and continuous Nov7 comment Arithmetic operations on sets With the notation suggested in my answer below, $\mathbb Z + \mathbb Z = \mathbb Z$, since every integer is the sum of two integers. Nov6 answered Arithmetic operations on sets Nov6 comment Give an example of an infinite compact set $A$ such that its supremum is not a limit point Have you been given an example of correct answer? Nov6 answered Prove that if $3\mid n^2$ then $3\mid n$. Nov6 comment Prove that if $3\mid n^2$ then $3\mid n$. what's your definition of prime number?