Hottest Questions This Month

100

votes

14

answers

18k

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The math behind Warren Buffet's famous rule – never lose money

answered 17 hours ago richard1941 486

46

votes

12

answers

6k

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Can area of rectangle be greater than the square of its diagonal?

geometry area

modified Dec 2 at 22:34 davidlowryduda♦ 74.2k

59

votes

6

answers

6k

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Japanese Temple Problem From 1844

geometry sangaku

modified Nov 24 at 15:01 Will Orrick 13.4k

38

votes

5

answers

7k

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Can a function have two derivatives?

calculus derivatives

answered Nov 27 at 23:35 Acccumulation 6,611

49

votes

3

answers

3k

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What is the formula for pi used in the Python decimal library?

sequences-and-series convergence computational-mathematics pi

modified 13 hours ago Raymond Hettinger 418

29

votes

7

answers

3k

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Are there any two numbers such that multiplying them together is the same as putting their digits next to each other?

natural-numbers

modified 2 days ago P T 105

27

votes

3

answers

4k

views

Is there a surface on which a hexagon can have all right angles?

geometry

modified Dec 2 at 10:57 amWhy 191k

39

votes

6

answers

7k

views

A way to find this shaded area without calculus?

geometry trigonometry area

modified Dec 4 at 9:52 Presh 562

69

votes

1

answer

4k

views

What does the mysterious constant marked by C on a slide rule indicate?

notation math-history constants

modified Nov 30 at 14:22 muru 133

22

votes

6

answers

2k

views

What are the possible values of these letters?

algebra-precalculus

modified Nov 15 at 15:19 costrom 406

17

votes

7

answers

2k

views

How can I find integers which satisfy $\frac{150+n}{15+n}=m$?

algebra-precalculus divisibility recreational-mathematics integers

modified yesterday Prem kumar 174

28

votes

6

answers

2k

views

Adult learner returning to maths [closed]

education

answered Nov 24 at 3:40 blaineh 119

11

votes

6

answers

1k

views

Does a mathematical proof in $\mathbb{C}$ imply a proof in the $\mathbb{R}$? [closed]

complex-numbers definition proof-theory

modified Nov 18 at 0:03 Xander Henderson 14.2k

25

votes

2

answers

4k

views

Prove that there exists a triangle which can be cut into 2005 congruent triangles.

geometry contest-math

modified Nov 27 at 0:23 achille hui 95k

11

votes

6

answers

1k

views

Given $\tan\alpha=2$, evaluate $\frac{\sin^{3}\alpha - 2\cos^{3}\alpha + 3\cos\alpha}{3\sin\alpha +2\cos\alpha}$

algebra-precalculus trigonometry

modified Dec 3 at 16:40 greedoid 36.5k

8

votes

5

answers

1k

views

$\lim\limits_{x\to 0} \frac{\tan x - \sin x}{x^3}$?

calculus limits proof-verification limits-without-lhopital

modified Nov 24 at 11:41 amWhy 191k

0

votes

6

answers

1k

views

A sequence in $\mathbb{R}$ that has no Cauchy subsequence

real-analysis sequences-and-series general-topology metric-spaces cauchy-sequences

modified Nov 24 at 7:17 user21820 38.2k

16

votes

3

answers

2k

views

Limit of a sequence of integrals involving continued fractions

calculus limits definite-integrals continued-fractions

modified Nov 20 at 9:20 Szeto 6,309

22

votes

2

answers

2k

views

A simple finite combinatorial sum I found, that seems to work, would have good reasons to work, but I can't find in the literature.

combinatorics summation binomial-coefficients

modified Dec 6 at 17:13 Marko Riedel 38.6k

18

votes

4

answers

1k

views

Give an example of: A group with an element A of order 3, an element B with order 4, where order of AB is less than 12

group-theory quotient-group

modified Dec 6 at 18:20 Will Orrick 13.4k

17

votes

7

answers

1k

views

Given a book with $100$ pages and a $100$ lemmas, prove that there is some lemma written on the same page as its index

combinatorics

modified 2 days ago timtfj 746

14

votes

6

answers

2k

views

Why do we automatically assume that when we divide a polynomial by a second degree polynomial the remainder is linear?

algebra-precalculus polynomials

answered 4 hours ago Ralf 17

7

votes

4

answers

2k

views

What is an example of a proof by minimal counterexample?

proof-writing examples-counterexamples infinite-descent

modified Nov 30 at 15:36 José Carlos Santos 146k

10

votes

2

answers

1k

views

Proof for Cauchy-Schwarz inequality for Trace [closed]

linear-algebra trace cauchy-schwarz-inequality

answered Nov 20 at 9:31 Kavi Rama Murthy 46.5k

17

votes

2

answers

3k

views

Can we make it equal to x?

algebra-precalculus nested-radicals infinitesimals

modified Nov 16 at 3:37 астон вілла олоф мэллбэрг 37.2k

8

votes

7

answers

2k

views

Why should a non-commutative operation even be called “multiplication”?

number-theory terminology noncommutative-algebra binary-operations

answered Nov 22 at 13:57 Broman 103

11

votes

2

answers

1k

views

4x4 Determinant [on hold]

linear-algebra determinant

modified Dec 10 at 8:03 Jean Marie 28.6k

10

votes

5

answers

2k

views

Where does one even need Bernoulli's Inequality?

real-analysis inequality

answered Dec 5 at 13:47 Cm7F7Bb 12.4k

19

votes

4

answers

1k

views

Average distance from center of circle

calculus probability geometry intuition

modified Nov 30 at 23:17 Mark Lakata 980

8

votes

2

answers

1k

views

Limit of matrix $A$ raised to power of $n$, as $n$ approaches infinity.

linear-algebra matrices limits

modified Dec 3 at 2:02 the_fox 2,319

5

votes

5

answers

1k

views

Can the empty set be the image of a function on $\mathbb{N}$? [closed]

functions elementary-set-theory

modified Nov 30 at 3:20 Brahadeesh 5,893

9

votes

5

answers

603

views

Proving that $\lim_{n\to\infty} \left(1+\frac{1}{f(n)}\right)^{g(n)} = 1$

calculus sequences-and-series limits exponentiation

modified Dec 2 at 9:28 Asaf Karagila♦ 300k

10

votes

4

answers

984

views

Convert infinite 2D plane integer coords to 1D number

algebraic-geometry

modified Nov 18 at 20:51 Kamil Maciorowski 2,499

14

votes

2

answers

747

views

Can an uncountable group have a countable number of subgroups? [on hold]

group-theory examples-counterexamples infinite-groups

modified Dec 9 at 3:01 Shaun 8,175

6

votes

6

answers

1k

views

Making sure if it is Cauchy

real-analysis cauchy-sequences

modified Nov 30 at 3:28 Matt A Pelto 2,338

9

votes

2

answers

775

views

When we say two fields are isomorphic, does that just mean they are isomophic as rings?

abstract-algebra field-theory

answered 2 days ago TonyK 41k

9

votes

3

answers

776

views

Is the characteristic polynomial of a matrix $\det(\lambda I-A)$ or$ \det(A-\lambda I)$?

matrices

modified Nov 18 at 21:43 Xander Henderson 14.2k

10

votes

6

answers

1k

views

Use the Euclidean Algorithm to find $a, b, c, d$ such that $225a + 360b +432c +480d = 3$

number-theory

modified Nov 20 at 19:03 Bill Dubuque 207k

7

votes

4

answers

1k

views

Is it possible for the bisection method to provide “fake” zeros

real-analysis analysis numerical-methods roots

modified Dec 2 at 22:33 Matt A Pelto 2,338

36

votes

2

answers

1k

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Did I just discover this integration formula?

calculus integration

answered Dec 9 at 16:22 David K 52k

4

votes

5

answers

1k

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Binomial Theorem with Three Terms

combinatorics binomial-coefficients

modified Nov 19 at 21:13 egreg 176k

12

votes

4

answers

791

views

How to find out the global minimum of the following expression

calculus

modified Nov 27 at 17:38 CaptainQuestion 90

9

votes

4

answers

2k

views

I have 100 boxes. C of them have a gift. I can open up to 16 boxes. What is the number of C that will give me probability over 0.5 to find a gift?

probability probability-theory

answered Nov 19 at 7:09 IanF1 1,324

24

votes

1

answer

680

views

$\lim_{n\to\infty} e^{-n} \sum_{k=0}^{n} \frac{n^k}{k!} = \frac{1}{2}$ - basic methods

calculus real-analysis limits eulers-constant

modified Nov 28 at 22:17 user128409235 76

6

votes

6

answers

989

views

Is there an easy way to see that binary expansion is unique? [closed]

elementary-number-theory binary

answered Nov 29 at 0:26 JonathanZ 2,089

6

votes

4

answers

2k

views

Why Can L'Hôpital's Rule Not be Applied to the Sum or Difference of Limits?

calculus limits

answered Nov 29 at 7:28 zhw. 71.1k

8

votes

4

answers

653

views

What is $\frac{1}{|{x}|}-\frac{x^2}{|x|^3}$?

algebra-precalculus absolute-value

modified Nov 24 at 13:36 user21820 38.2k

6

votes

2

answers

1k

views

A pattern in determinants of Fibonacci numbers?

linear-algebra determinant fibonacci-numbers

modified Dec 3 at 9:02 Martin Sleziak 44.6k

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