User skyking

43 votes

How far is the list of known primes known to be complete?

prime-numbers

answered Jul 7, 2016 at 11:24

14 votes

"Where" exactly are complex numbers used "in the real world"?

answered Mar 8, 2016 at 10:24

14 votes

Prove the series $\sum_{n=1}^{\infty}\frac{1}{{5^n}^!}$ converges to an irrational number

calculus sequences-and-series recreational-mathematics rationality-testing

answered Jul 21, 2017 at 6:08

12 votes

Problem with the compact version of the definition for "exactly one"

predicate-logic first-order-logic

answered Aug 29, 2017 at 6:17

12 votes

Closed property of nonempty finite set

real-analysis

answered Oct 25, 2017 at 11:19

12 votes

Accepted

Difference between units and dimensions

unit-of-measure dimensional-analysis

answered May 22, 2017 at 10:45

11 votes

it is correct to write 0,000 or just 0?

convention

answered Jan 16, 2017 at 9:28

10 votes

Accepted

What is this equality: $\frac{\theta/(\theta+1)^{x+k}}{\theta^k}=(\frac1{\theta+1})^k(\frac{\theta}{\theta+1})^x$? How to work it out?

algebra-precalculus fractions

answered May 9, 2017 at 11:29

9 votes

What is the main difference between a vector space and a field?

vector-spaces field-theory

answered Oct 6, 2015 at 11:35

9 votes

Does the inverse of the matrix always rely on the determinant of a matrix?

abstract-algebra matrices group-theory inverse

answered Sep 28, 2015 at 11:35

8 votes

Probability of $0$

probability

answered Aug 11, 2017 at 6:16

8 votes

Accepted

High school geometry proof help

geometry

answered Sep 28, 2017 at 6:44

8 votes

why is there no order in metric spaces?

metric-spaces order-theory

answered Sep 10, 2015 at 11:19

8 votes

Accepted

Showing that two definitions of $\limsup$ are equivalent

real-analysis definition limsup-and-liminf

answered Nov 6, 2015 at 9:47

8 votes

Accepted

How many right triangles can be made using the vertices of a regular $10$-gon?

combinatorics recreational-mathematics

answered Apr 10, 2017 at 12:33

7 votes

Accepted

How many arrangements of MATHEMATICS are there in which each consonant is adjacent to a vowel?

combinatorics

answered Sep 7, 2015 at 10:32

7 votes

Zero divided by zero must be equal to zero

proof-verification fake-proofs

answered Dec 2, 2015 at 11:10

7 votes

Why do we want the Axiom of the Power Set?

set-theory axioms foundations

answered Jan 20, 2016 at 7:57

7 votes

Accepted

How many ways are there for arranging letters of the word AMAZING?

combinatorics discrete-mathematics permutations combinations

answered Mar 16, 2017 at 7:51

7 votes

When is a proof or definition formal?

proof-writing definition

answered Apr 6, 2017 at 7:22

7 votes

How does the axiom of regularity make sense?

logic set-theory axioms

answered May 18, 2017 at 14:25

7 votes

Accepted

If the value of a polynomial is $0$ for $x=1$ , why do we say that $(x-1)$ is a factor

algebra-precalculus polynomials

answered Jul 12, 2017 at 8:15

6 votes

$A \in B$ vs. $A \subset B$ for proofs

elementary-set-theory proof-writing

answered Sep 11, 2015 at 9:31

6 votes

Isn't the Continuity Concept Redundant (up to definitions)?

analysis functions continuity

answered Sep 30, 2015 at 13:37

6 votes

How many passwords can be formed from this maze?

combinatorics discrete-mathematics recreational-mathematics

answered Nov 28, 2015 at 12:58

6 votes

Accepted

De Moivre Theorem. Find the exact values of the solutions of the equations.

algebra-precalculus trigonometry complex-numbers

answered Dec 1, 2015 at 7:18

6 votes

Accepted

A finite Hausdorff space is discrete

general-topology separation-axioms

answered Dec 11, 2015 at 14:33

6 votes

Accepted

if |f| is periodic then f is periodic

absolute-value periodic-functions

answered Nov 4, 2015 at 10:20

6 votes

Accepted

Why is rotation about the y axis in $\mathbb{R^3}$ different from rotation about the x and y axis.

linear-algebra

answered Nov 26, 2015 at 10:06

6 votes

Why can't we remove the sqrt from rms?

statistics chemistry

answered Jan 16, 2017 at 9:39

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790 Answers

How far is the list of known primes known to be complete?

"Where" exactly are complex numbers used "in the real world"?

Prove the series $\sum_{n=1}^{\infty}\frac{1}{{5^n}^!}$ converges to an irrational number

Problem with the compact version of the definition for "exactly one"

Closed property of nonempty finite set

Difference between units and dimensions

it is correct to write 0,000 or just 0?

What is this equality: $\frac{\theta/(\theta+1)^{x+k}}{\theta^k}=(\frac1{\theta+1})^k(\frac{\theta}{\theta+1})^x$? How to work it out?

What is the main difference between a vector space and a field?

Does the inverse of the matrix always rely on the determinant of a matrix?

Probability of $0$

High school geometry proof help

why is there no order in metric spaces?

Showing that two definitions of $\limsup$ are equivalent

How many right triangles can be made using the vertices of a regular $10$-gon?

How many arrangements of MATHEMATICS are there in which each consonant is adjacent to a vowel?

Zero divided by zero must be equal to zero

Why do we want the Axiom of the Power Set?

How many ways are there for arranging letters of the word AMAZING?

When is a proof or definition formal?

How does the axiom of regularity make sense?

If the value of a polynomial is $0$ for $x=1$ , why do we say that $(x-1)$ is a factor

$A \in B$ vs. $A \subset B$ for proofs

Isn't the Continuity Concept Redundant (up to definitions)?

How many passwords can be formed from this maze?

De Moivre Theorem. Find the exact values of the solutions of the equations.

A finite Hausdorff space is discrete

if |f| is periodic then f is periodic

Why is rotation about the y axis in $\mathbb{R^3}$ different from rotation about the x and y axis.

Why can't we remove the sqrt from rms?