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355durch113
  • Member for 10 years, 3 months
  • Last seen more than 2 years ago
  • Vienna, Austria
7 votes
2 answers
3k views

Difference in use between $d$, $\partial$, $\operatorname d$, $\varDelta$ and $D$ for derivatives.

5 votes
3 answers
420 views

Probability that out of 600 crabs 60 are still alive after 9 months.

5 votes
3 answers
80 views

Is it allowed to "ignore" $\lim$ in this case?

5 votes
1 answer
110 views

Is there a mathematical property which could help "sum up" information from certain matrix areas?

4 votes
2 answers
114 views

How to generate another solution $\in \mathbb N$ of $x^2=2y^2+7$ knowing one.

4 votes
5 answers
570 views

How to show that $7\mid a^2+b^2$ implies $7\mid a$ and $7\mid b$?

4 votes
5 answers
3k views

How can infinity be an accumulation point?

4 votes
2 answers
118 views

How do you refer to this Term in English?

4 votes
2 answers
91 views

Is this a legal transformation?

4 votes
1 answer
45 views

For which real $x$ is this (monster) series convergent?

3 votes
1 answer
73 views

Equivalence of limits $\lim\limits_{x\searrow 0}\lim\limits_{\xi\searrow x}g(x,\xi)=\lim\limits_{x\searrow 0}\lim\limits_{\xi\searrow 0}g(x,\xi)$?

3 votes
2 answers
71 views

Which integer sequence starts with small elements, and stays there for a (really) long time, but eventually escapes the initial area?

2 votes
2 answers
4k views

How to solve the differential equation $y'=y(1-y)$.

2 votes
2 answers
1k views

Proof that $f'(0)$ of an even function is always $0$.

2 votes
1 answer
69 views

(Generalization) Possibilities of picking k nonconsecutive from n consecutive numbers.

2 votes
1 answer
369 views

If $G/Z(G)$ is cyclic, why is $G$ only abelian and not also cyclic?

2 votes
2 answers
62 views

Riemann sum for $\int_0^a e^x dx$.

2 votes
2 answers
65 views

Let $(x,y)$ be the smallest solution $\in \mathbb N^+$ of $x^2+xy-y^2=0$, then $y-x<x$. Why?

2 votes
2 answers
339 views

Are these two definitions of differentiability equal?

2 votes
1 answer
59 views

"Number of zeroes of $f \leq \deg f$" used in a proof.

2 votes
3 answers
49 views

Hölder inequality in case $q=p=2$.

2 votes
0 answers
39 views

Are Riemann-integrals supposed to have a finite value?

2 votes
1 answer
408 views

Closed graph theorem: How do domain and codomain affect continuity?

2 votes
1 answer
842 views

Congruence of 2 fractions—how to properly rewrite in terms without modulo?

2 votes
4 answers
1k views

What is the direction along the edge of a circle called (in English and by chance German)?

2 votes
4 answers
46 views

Matrix that moves the graph of a polynomial.

2 votes
0 answers
363 views

Help with proof about solvability of linear diophantine equation.

2 votes
1 answer
59 views

Verify combinatoric argumentation.

2 votes
2 answers
43 views

Shown that this matrix is a representative of a group.

2 votes
1 answer
142 views

Integral of $xyz$ over $B=\{0<x<1, 0<y, 0<z, 0<x+y<1\}$