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Nov
27
answered How to show that $\lim_{x\to \infty}f'(x)=0$
Nov
27
answered Continuity of addition under the lower limit topology
Nov
25
answered Possible Intersection of Intervals
Nov
25
comment Could someone explain the Lagrangian Method?
the tangent to the constraint $g=0$
Nov
23
answered Could someone explain the Lagrangian Method?
Nov
23
answered Formula of regular 2m-gon inscribed in a unit cirlce
Nov
23
revised How can I find the example of $f(x)$ such that $\,\lim_{x\to\infty}f(x) \neq 0$?
deleted 70 characters in body
Nov
23
answered How can I find the example of $f(x)$ such that $\,\lim_{x\to\infty}f(x) \neq 0$?
Nov
22
answered What is the difference between convergence of a sequence and convergence of a series?
Nov
20
answered Proof $x=\sin(x+1)$ has one solution in $\mathbb{R}$
Nov
18
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.
Nov
18
answered Studying the differentiability of a function at a point $(a_{1},a_{2})$
Nov
18
answered Proving the convergence/divergence of a seemingly oscillating series
Nov
18
answered Rolling ellipse on line - tangent and normal of roulette
Nov
18
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 $FK$.
Nov
17
comment Prove or disprove: functions
Maybe $X'$ is the complementary set of $X$?
Nov
11
revised About Banach Spaces And Absolute Convergence Of Series
typo
Nov
11
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.
Nov
7
comment Limit of derivatives and continuous
But, again, this is true only if the limit of $f'$ exists and it is finite.
Nov
7
comment Limit of derivatives and continuous
It is possible that the limit of $f$ is infinite and the limit of $f'$ exists. Take $f(x) = 1/(1-x)$.