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University of Florence


Nov
7
comment Limit of derivatives and continuous
Continuity of a function tells nothing in the points outside the domain.
Nov
7
answered Limit of derivatives and continuous
Nov
7
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.
Nov
6
answered Arithmetic operations on sets
Nov
6
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?
Nov
6
answered Prove that if $3\mid n^2 $ then $3\mid n $.
Nov
6
comment Prove that if $3\mid n^2 $ then $3\mid n $.
what's your definition of prime number?
Nov
6
comment If $f$ is bounded and twice differentiable in $\mathbb{R}$, show that there exists $\xi\in\mathbb{R}$, s.t. $f''(\xi)=0$.
Lemma 3 is false: take $f(x)=atan(x)$
Nov
6
comment If $f$ is bounded and twice differentiable in $\mathbb{R}$, show that there exists $\xi\in\mathbb{R}$, s.t. $f''(\xi)=0$.
en.wikipedia.org/wiki/Darboux%27s_theorem_%28analysis%29
Nov
6
comment If $f$ is bounded and twice differentiable in $\mathbb{R}$, show that there exists $\xi\in\mathbb{R}$, s.t. $f''(\xi)=0$.
The intermediate value theorem is true for the derivative of a function even if the derivative is not continuous.
Nov
6
revised If $f$ is bounded and twice differentiable in $\mathbb{R}$, show that there exists $\xi\in\mathbb{R}$, s.t. $f''(\xi)=0$.
added 40 characters in body
Nov
6
answered If $f$ is bounded and twice differentiable in $\mathbb{R}$, show that there exists $\xi\in\mathbb{R}$, s.t. $f''(\xi)=0$.
Nov
4
revised Why is $e^{-f(z)} = 1-z$, when $f(z)=\sum_{n=1}^\infty \frac{z^n}{n}$?
edited body; edited title
Nov
4
asked Pull back of a vector representing a 2-form in $\mathbb R^3$
Oct
30
answered Partitions of $[0,1]$
Oct
28
comment Replace a sum with an integral $\sum\rightarrow \int$
What does the arrow mean?
Oct
28
answered Find the minimum distance between the curves $y^2-xy-2x^2 =0$ and $y^2=x-2$
Oct
28
awarded  geometry
Oct
27
revised Intuition behind a certain limit.
added 188 characters in body
Oct
27
answered Intuition behind a certain limit.