User John Bentin

131 votes

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Why is the Penrose triangle "impossible"?

answered Jul 2, 2020 at 18:13

74 votes

Find $xy+yz+zx$ given systems of three homogenous quadratic equations for $x, y, z$

answered Feb 9, 2018 at 17:21

35 votes

To sum $1+2+3+\cdots$ to $-\frac1{12}$

answered Sep 8, 2012 at 18:05

32 votes

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When do two functions become equal?

answered Aug 19, 2015 at 20:14

32 votes

Is sudoku only one puzzle?

answered Aug 20 at 5:45

31 votes

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What are usual notations for surjective, injective and bijective functions?

answered Jun 21, 2011 at 12:01

26 votes

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"a Euler graph" or "an Euler graph"?

answered Jul 4, 2023 at 8:53

25 votes

Theorems' names that don't credit the right people

answered Jun 3, 2013 at 21:18

23 votes

What are some surprising appearances of $e$?

answered Feb 8, 2016 at 14:56

17 votes

Why can't we order Complex Numbers?

answered May 15, 2016 at 19:56

14 votes

How did the notation "ln" for "log base e" become so pervasive?

answered Aug 6, 2010 at 15:43

14 votes

Piecewise functions: Got an example of a real world piecewise function?

answered Jun 5, 2012 at 12:59

14 votes

How to integrate $\int 1/(x^7 -x) dx$?

answered Nov 14, 2012 at 21:57

13 votes

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How do I distinguish between "e" the natural log base and a variable conventionally referred to as "e"?

answered Jul 21 at 15:22

12 votes

How can five sticks with coinciding ends be arranged in space such that they are at their maximum angles to each other?

answered Apr 20 at 5:35

12 votes

A vector is defined to have a magnitude and a direction, but the zero vector has no single direction. So, how is the zero vector a vector?

answered Aug 31, 2019 at 7:18

12 votes

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Is this mechanical puzzle (Loony loop) solvable?

answered Jul 13, 2011 at 13:17

12 votes

Lagrange's Trigonometric Identity

answered May 18, 2014 at 17:18

11 votes

Why can't a perpetual motion polyhedron exist?

answered Jan 16, 2015 at 16:42

11 votes

Accepted

How many lines can be equidistant from 3 points?

answered Feb 2, 2012 at 8:37

11 votes

Notation for an interval when you don't know which bound is greater

answered Jun 8, 2018 at 16:02

11 votes

Every number is the sum of three squares with signs

answered Feb 15, 2017 at 10:08

10 votes

In a math paper, what is a remark?

answered Feb 25, 2018 at 22:05

10 votes

Formal definition of “counterexample”.

answered Jul 17, 2016 at 18:16

9 votes

What happens if you repeatedly take the arithmetic mean and geometric mean?

answered Dec 8, 2015 at 16:39

9 votes

Set builder notation, left or right of :| convention

answered May 26, 2012 at 9:08

9 votes

Difference between "intercept" and "intersect"

answered Oct 18, 2012 at 7:27

9 votes

Accepted

Euler Vs. Diderot

answered Jan 4, 2015 at 15:32

8 votes

Two dice thrown, one comes up 6

answered Aug 1, 2014 at 6:37

8 votes

Mathematical writing: why should we not use the phrase "we have that"?

answered Jul 20, 2013 at 7:22

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557 Answers

Why is the Penrose triangle "impossible"?

Find $xy+yz+zx$ given systems of three homogenous quadratic equations for $x, y, z$

To sum $1+2+3+\cdots$ to $-\frac1{12}$

When do two functions become equal?

Is sudoku only one puzzle?

What are usual notations for surjective, injective and bijective functions?

"a Euler graph" or "an Euler graph"?

Theorems' names that don't credit the right people

What are some surprising appearances of $e$?

Why can't we order Complex Numbers?

How did the notation "ln" for "log base e" become so pervasive?

Piecewise functions: Got an example of a real world piecewise function?

How to integrate $\int 1/(x^7 -x) dx$?

How do I distinguish between "e" the natural log base and a variable conventionally referred to as "e"?

How can five sticks with coinciding ends be arranged in space such that they are at their maximum angles to each other?

A vector is defined to have a magnitude and a direction, but the zero vector has no single direction. So, how is the zero vector a vector?

Is this mechanical puzzle (Loony loop) solvable?

Lagrange's Trigonometric Identity

Why can't a perpetual motion polyhedron exist?

How many lines can be equidistant from 3 points?

Notation for an interval when you don't know which bound is greater

Every number is the sum of three squares with signs

In a math paper, what is a remark?

Formal definition of “counterexample”.

What happens if you repeatedly take the arithmetic mean and geometric mean?

Set builder notation, left or right of :| convention

Difference between "intercept" and "intersect"

Euler Vs. Diderot

Two dice thrown, one comes up 6

Mathematical writing: why should we not use the phrase "we have that"?