User ulead86 - Mathematics Stack Exchange

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	1,344 reputation	bio	website	doesnotexist	visits	member for	1 year, 10 months
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2

12

votes

1

answer

246

views

Chebyshev: Proof $\prod \limits_{p \leq 2k}{\;} p > 2^k$

jan 3 '12 at 7:34 J. M. 38.9k

1

7

votes

1

answer

322

views

Proof: If $n \in \mathbb{N}$ is not the sum of two squares, then $n$ is also not the sum of two rational squares

homework number-theory

dec 11 '11 at 6:15 Srivatsan 15.6k

1

5

votes

5

answers

90

views

Proof: $\vec x,\vec y \perp \vec z \Rightarrow \vec x || \vec y$

homework geometry

apr 29 at 11:19 rschwieb 21k

1

4

votes

1

answer

66

views

Dice game modelling: Lose everything on “3”, double everything on “1” or “6”

probability-distributions stochastic-processes dice

mar 12 at 18:27 Shyam 1,523

1

4

votes

4

answers

74

views

Bell Numbers: How to put EGF $e^{e^x-1}$ into a series?

power-series generating-functions stochastic-calculus

jan 28 at 18:09 Steven Stadnicki 14.2k

4

votes

1

answer

158

views

Sufficient / necessary conditions for $f \circ g$ being injective, surjective or bijective

functions elementary-set-theory

oct 7 at 15:45 Martin Sleziak 20.3k

4

votes

1

answer

193

views

Proof: $\phi(n)=\sum\limits_{k=1}^{n-1} \left\lfloor\frac{1}{\operatorname{gcd}(n,k)} \right\rfloor$

number-theory totient-function

oct 28 '11 at 12:55 Daniel Freedman 600

3

votes

1

answer

27

views

Find $ \vec{z} \parallel \vec{x}$ and $\vec{y}-\vec{z} \perp \vec{x}$

homework linear-algebra geometry

apr 16 at 16:15 A.P. 1,264

3

votes

2

answers

68

views

Counterexample for $R(4,4) \neq 8$

graph-theory coloring ramsey-theory

apr 16 at 13:57 Douglas S. Stones 11.2k

3

votes

2

answers

64

views

Why doesn't work Integer factorization for fields?

abstract-algebra prime-numbers

oct 26 at 7:21 Martin Brandenburg 22.9k

1

3

votes

4

answers

171

views

Proof: If $n=ab$ then $2^a-1 \mid 2^n-1$

elementary-number-theory

dec 13 '11 at 18:43 Community♦ 1

3

votes

3

answers

172

views

Proofs from the BOOK: Bertrand's postulate: $\binom{2m+1}{m}\leq 2^{2m}$

number-theory binomial-coefficients

nov 10 '11 at 15:32 sdcvvc 4,669

3

votes

2

answers

208

views

Proofs from the BOOK: Bertrand's postulate Part 3: $\frac{2}{3}n<p \leq n \rightarrow$ no p divides $\binom{2n}{n}$

number-theory prime-numbers

nov 8 '11 at 14:38 Martin Sleziak 20.3k

2

votes

1

answer

286

views

Prove $O(x)+O(x^2)=O(x^2)$ (Big O Notation)

homework asymptotics

apr 13 at 10:00 Ali Amiri 549

2

votes

2

answers

72

views

Prove an inequality in $\mathbb{R}$

geometry metric-spaces

apr 10 at 19:48 Dominic Michaelis 11.9k

2

votes

1

answer

34

views

probability theory: compute E(X) and $\sigma^2$

probability

dec 17 at 17:48 André Nicolas 161k

2

votes

3

answers

247

views

Show that every power of $2$ is sum of two squares.

homework elementary-number-theory

jan 19 '12 at 18:55 Community♦ 1

2

votes

2

answers

233

views

Proof existence of field extension of $\mathbb{F}_p$ containing the $r$-th primitive root of unity

abstract-algebra field-theory finite-fields roots

jan 7 '12 at 8:58 Pierre-Yves Gaillard 8,487

2

votes

1

answer

75

views

How to get “N” from $k=\log_2(N)$

algebra-precalculus logarithms

dec 28 '11 at 23:43 J. M. 38.9k

2

votes

3

answers

302

views

Continued fraction: Show $\sqrt{n^2+2n}=[n; \overline{1,2n}]$

homework continued-fractions

dec 2 '11 at 5:42 Aaron 6,642

2

votes

1

answer

97

views

Reciprocal of a continued fraction

homework number-theory continued-fractions

nov 27 '11 at 14:32 J. M. 38.9k

2

votes

1

answer

76

views

Show $p(n)=n(p_{n-1}+p_{n-2})+(n-1)p_{n-3}+(n-2)p_{n-4}+…+3p_1+2p_0+2$

homework number-theory continued-fractions

nov 26 '11 at 17:17 Brian M. Scott 155k

2

votes

1

answer

183

views

Prove that $e^{\sqrt{\log x }}=O(x^n)$

homework asymptotics

nov 25 '11 at 19:25 Beni Bogosel 10.5k

2

votes

1

answer

163

views

Proofs from the BOOK: Bertrand's postulate: proof $\lfloor \frac{2n}{p^k} \rfloor - 2 \lfloor \frac{n}{p^k} \rfloor= 2$

number-theory

nov 9 '11 at 8:42 Aleks Vlasev 530

1

vote

1

answer

266

views

Analytic proof for Circles of Apollonius

geometry analytic-geometry

may 14 at 18:56 Marcelo 1

1

vote

2

answers

44

views

Understanding the boundary of a set

general-topology rational-numbers

apr 15 at 15:30 HSN 564

1

vote

1

answer

41

views

Proof: $a<b$ and $ b<c$, then also $a<c$ (for partially ordered set of $M$)

linear-algebra order-theory

apr 1 at 20:08 Peter Tamaroff 25.9k

1

vote

3

answers

78

views

Proof: Two non identical circles have at most 2 same points

geometry analytic-geometry

mar 10 at 19:15 André Nicolas 161k

1

vote

3

answers

69

views

Triangle $\Delta ABC$: Proof $\angle ADB<\angle ACB$

homework geometry

feb 21 at 14:43 amWhy 55k

1

vote

1

answer

55

views

Hypothesis testing, find out critical value $c$

homework probability statistics

jan 21 at 13:44 ulead86 1,344

ulead86

54 Questions