User Klaus - Mathematics Stack Exchange

bio	website
	location
	age
visits	member for	2 years, 10 months
	seen	21 hours ago
stats	profile views	152

	1,066 reputation	bio	website		visits	member for	2 years, 10 months
317 badges		location			seen	21 hours ago

70

162

votes

13

answers

12

kviews

Is value of $\pi = 4$?

geometry analysis pi fake-proofs

may 21 at 16:03 robjohn♦ 60.1k

82

131

votes

9

answers

8

kviews

What's an intuitive way to think about the determinant?

linear-algebra intuition determinant

may 13 at 7:14 MJD 21.1k

34

88

votes

3

answers

3

kviews

How to show $e^{e^{e^{79}}}$ is not an integer

number-theory transcendence-theory

jun 16 '11 at 0:28 Gerry Myerson 86k

40

78

votes

31

answers

6

kviews

Can you provide me historical examples of pure mathematics becoming “useful”?

soft-question math-history big-list applications

feb 26 at 16:22 KeithS 1,051

51

55

votes

26

answers

5

kviews

What is the single most influential book every mathematician should read?

soft-question big-list reference-request

22h ago Marcus Antoninus 41

34

46

votes

17

answers

4

kviews

Striking applications of integration by parts

calculus big-list

may 3 at 13:19 DepeHb 494

37

44

votes

4

answers

2

kviews

What are the Axiom of Choice and Axiom of Determinacy?

set-theory intuition axiom-of-choice

nov 26 at 11:34 Matt N. 15.3k

14

42

votes

7

answers

2

kviews

Surprise exam paradox?

induction paradox

jan 10 '12 at 19:59 Chelonian 221

33

42

votes

8

answers

2

kviews

Intuition in algebra?

abstract-algebra soft-question intuition

may 13 '12 at 1:21 AbstractionOfMe 184

9

33

votes

1

answer

1

kviews

Is Lagrange's theorem the most basic result in finite group theory?

abstract-algebra group-theory teaching proof-strategy

may 10 '11 at 20:41 joriki 92.8k

20

33

votes

12

answers

1

kviews

Resources for a curious beginner mathematician

education

nov 17 '11 at 22:50 Dave L. Renfro 6,611

6

29

votes

2

answers

805

views

How much rigour is necessary?

algebraic-topology soft-question

jul 1 at 5:01 Mathemagician1234 3,774

18

25

votes

14

answers

3

kviews

What should be in every grad student's library?

big-list reference-request

may 5 at 17:30 TMM 7,156

5

25

votes

2

answers

793

views

Elementary proof that $2x^2+xy+3y^2$ represents infinitely many primes?

number-theory prime-numbers quadratic-forms

oct 10 '11 at 22:00 J. M. 39k

23

21

votes

11

answers

2

kviews

Fun Linear Algebra Problems

linear-algebra big-list

jun 11 '11 at 7:41 Joel Cohen 3,669

12

20

votes

5

answers

803

views

Does $G\cong G/H$ imply that $H$ is trivial?

group-theory

jan 31 at 11:23 user1729 3,364

9

20

votes

13

answers

2

kviews

How to avoid arithmetic mistakes?

arithmetic

may 10 '12 at 1:59 Alex 4,599

3

18

votes

16

answers

2

kviews

An example for a calculation where imaginary numbers are used but don't occur in the question or the solution.

complex-numbers examples-counterexamples teaching

nov 10 at 17:06 Seirios 8,977

11

17

votes

4

answers

987

views

Does every set have a group structure?

group-theory set-theory axiom-of-choice

feb 10 '12 at 14:37 spohreis 1,479

13

17

votes

14

answers

3

kviews

Intuitive understanding of the derivatives of $\sin x$ and $\cos x$

calculus trigonometry

aug 16 at 22:37 Peter Tamaroff 26.2k

1

15

votes

6

answers

833

views

Simple proof that $8\left(\frac{9}{10}\right)^8 > 1$

inequality fractions powers

nov 24 '11 at 4:49 N. S. 28.1k

7

15

votes

4

answers

390

views

Material in a first course in algebraic geometry?

reference-request algebraic-geometry

mar 1 at 2:39 Victor 1,278

7

15

votes

1

answer

1

kviews

Is the following matrix invertible?

linear-algebra matrices

jul 27 at 1:46 torrho 93

8

14

votes

4

answers

1

kviews

How to prove periodicity of $\sin(x)$ or $\cos(x)$ starting from the Taylor series expansion?

calculus real-analysis

nov 9 '11 at 4:32 Srivatsan 15.7k

5

13

votes

4

answers

422

views

If $[G:H]=n$, then $g^{n!}\in H$ for all $g\in G$.

abstract-algebra group-theory

may 31 '12 at 15:31 Solomone Pule 1

14

12

votes

5

answers

1

kviews

Methods to see if a polynomial is irreducible

abstract-algebra polynomials

may 4 '11 at 8:10 Bruno Stonek 3,148

5

12

votes

4

answers

946

views

Groups of order $pq$ with out using Sylow theorems

group-theory

sep 28 '11 at 16:28 Arturo Magidin 158k

8

12

votes

3

answers

921

views

Fundamental Theorem of Calculus

real-analysis soft-question

jun 24 '11 at 19:23 Arturo Magidin 158k

2

12

votes

2

answers

497

views

Fibonacci[n]-1 is always composite for n>6. why?

fibonacci-numbers

jan 9 '11 at 17:23 Qiaochu Yuan 118k

6

12

votes

4

answers

1

kviews

If $a | m$ and $(a + 1) | m$, prove $a(a + 1) | m$.

number-theory

jan 25 at 0:45 Austin Mohr 11.7k

Klaus

69 Favorites