Reputation
2,015
Top tag
Next privilege 2,500 Rep.
Create tag synonyms
9 25
Impact
~28k people reached

### Questions (70)

 12 Chebyshev: Proof $\prod \limits_{p \leq 2k}{\;} p > 2^k$ 7 Proof: $\phi(n)=\sum\limits_{k=1}^{n-1} \left\lfloor\frac{1}{\operatorname{gcd}(n,k)} \right\rfloor$ 7 Proof: If $n \in \mathbb{N}$ is not the sum of two squares, then $n$ is also not the sum of two rational squares 5 Solving congruences 5 Proof: $\vec x,\vec y \perp \vec z \Rightarrow \vec x || \vec y$

### Reputation (2,015)

 +5 $x,y$ are linearly depending $\Leftrightarrow ||=||x|| \cdot ||y||$ +21 maximum area of semi-circle in square +10 Are contractible open sets in $\mathbb{R}^n$ homeomorphic to $\mathbb R^n$? +5 Proof: $\phi(n)=\sum\limits_{k=1}^{n-1} \left\lfloor\frac{1}{\operatorname{gcd}(n,k)} \right\rfloor$

 23 Are contractible open sets in $\mathbb{R}^n$ homeomorphic to $\mathbb R^n$? 10 Proving $\sum\limits_{k=1}^{n}{\frac{1}{\sqrt{k}}\ge\sqrt{n}}$ with induction 7 Is the function $\frac{x^2-x-2}{x-2}$ continuous? 6 Trisecting a paper using hand and without using a ruler or compass 4 Direct proof: $\sqrt{13}$ is irrational

### Tags (75)

 23 general-topology × 2 10 summation × 2 14 calculus × 5 10 induction 12 geometry × 31 8 elementary-number-theory × 9 11 inequality × 4 8 recreational-mathematics × 2 10 algebra-precalculus × 7 6 integration × 6

### Accounts (6)

 Mathematics 2,015 rep 925 English Language & Usage 266 rep 37 TeX - LaTeX 259 rep 17 German Language 236 rep 13 Cross Validated 101 rep 2