Hagen von Eitzen
Reputation
94/100 score
10 135 268
Impact
~1.3m people reached

 181 How can a piece of A4 paper be folded in exactly three equal parts? 131 Can you be 1/12th Cherokee? 114 Why is empty set an open set? 81 Why do people lose in chess? 81 How do I convince my students that the choice of variable of integration is irrelevant?

### Reputation (139,335)

 +15 let $α, β ∈\operatorname{ End}(V )$ satisfy $3α^3 + 7α^2 − 2αβ + 4α − σ_1 = σ_0$. Show that $αβ = βα$. +15 $O_k=\mathbb{Z}[\sqrt{d}]$, whenever $K=\mathbb{Q}(\sqrt{d})$ and $d\neq 1$ mod $4$ +25 Sequences: $\frac{|x_n|}{1+|x_n|}\to0$ implies $x_n\to0$? +10 Sums of two irreducible polynomials over $\mathbb{Z}$

### Questions (5)

 82 Connected metric spaces with disjoint open balls 12 If $f(x)\to 0$ as $x\to\infty$ and $f''$ is bounded, show that $f'(x)\to0$ as $x\to\infty$ 9 Construct quadrangle with given angles and perpendicular diagonals 7 Connected length space with disjoint open ball property 4 Lottery with coupon collecting - what prices are fair?

### Tags (551)

 1k real-analysis × 587 674 general-topology × 245 1k abstract-algebra × 457 664 linear-algebra × 306 851 calculus × 364 654 sequences-and-series × 245 798 group-theory × 298 645 number-theory × 208 779 elementary-number-theory × 234 551 probability × 254

### Accounts (63)

 Mathematics 139,335 rep 10135268 German Language 1,428 rep 211 Stack Overflow 571 rep 414 TeX - LaTeX 347 rep 19 Super User 323 rep 113