User Ant

111 votes

'Obvious' theorems that are actually false

answered Jun 5, 2014 at 10:01

47 votes

Accepted

Why is uniqueness important for PDEs?

answered Jul 19, 2016 at 8:26

46 votes

Accepted

Can a number have infinitely many digits before the decimal point?

answered Sep 24, 2014 at 12:49

30 votes

Accepted

Why can the determinant be assumed to be 0?

answered Jan 24, 2018 at 12:32

28 votes

"What if" math joke: the derivative of $\ln(x)^e$

answered Mar 7, 2015 at 11:43

23 votes

Accepted

Can $n^2+4n$ be a perfect square?

answered Jun 22, 2015 at 22:43

20 votes

How to find Laurent series Expansion

answered Mar 8, 2015 at 10:32

20 votes

Accepted

If $A=AA^{\top}$, show that $A^2=A$

answered Jun 30, 2014 at 17:11

18 votes

Why doesn't L'Hôpital's rule work in this case?

answered Jun 28, 2015 at 15:02

18 votes

Formulae of the Year $2016$

answered Dec 15, 2015 at 19:25

15 votes

Why do we need rationalisation?

answered Jan 11, 2017 at 18:40

14 votes

Why do some integrals and derivatives have absolute values?

answered Dec 11, 2016 at 18:39

13 votes

Problem understanding the concept of a union

answered Sep 17, 2015 at 20:14

13 votes

Accepted

Repeated application of L'Hôpital on polynomials doesn't always work?

answered Jun 11, 2016 at 12:43

12 votes

Accepted

How is substituting $-y$ for $y$ with $y \neq 0$ legal?

answered Jan 4, 2016 at 8:03

12 votes

Accepted

If $\sum_{i = 1}^n a_i b_i = \sum_{i = 1}^n a_i^2 = \sum_{i = 1}^n b_i^2$, then $a_i = b_i$ for all $i$.

answered Aug 15, 2016 at 12:48

12 votes

Is there a real number which comes just after a particular real number?

answered May 30, 2015 at 18:21

11 votes

Accepted

Two divergent series such that their product is convergent

answered Jul 5, 2015 at 8:06

11 votes

Accepted

Does $1^i$ and $1^{\frac{0}{0}}$ also give $1$ again?

answered Apr 30, 2015 at 9:57

10 votes

Accepted

Does $\int_{1}^{\infty} g(x)\ dx$ imply $\lim\limits_{x\to \infty}g(x)=0$?

answered May 3, 2017 at 9:16

10 votes

Convert from base $10$ to base $5$

answered Apr 8, 2014 at 20:20

9 votes

What is the motivation behind the study of sequences?

answered Nov 30, 2015 at 10:06

9 votes

quick question on an example of the derivative as a linear map.

answered Feb 11, 2016 at 21:37

9 votes

To prove the sum is convergent

answered Jul 23, 2014 at 23:40

8 votes

Accepted

If $a>b$ then $a^a>b^a. $

answered Aug 30, 2016 at 14:11

8 votes

Accepted

Computing two variables limit

answered May 10, 2015 at 9:27

8 votes

Accepted

What is the difference between identically distributed random variables ?

answered Jun 18, 2018 at 16:38

7 votes

Calculate the following integral

answered Jul 29, 2016 at 11:21

7 votes

Why the probability $P(X>Y)$ is the same as $P(\log X > \log Y)$?

answered Jun 28, 2016 at 10:57

7 votes

Accepted

Is $|z^2|$ entire function?

answered Jun 16, 2016 at 14:57

Stack Exchange Network

522 Answers

'Obvious' theorems that are actually false

Why is uniqueness important for PDEs?

Can a number have infinitely many digits before the decimal point?

Why can the determinant be assumed to be 0?

"What if" math joke: the derivative of $\ln(x)^e$

Can $n^2+4n$ be a perfect square?

How to find Laurent series Expansion

If $A=AA^{\top}$, show that $A^2=A$

Why doesn't L'Hôpital's rule work in this case?

Formulae of the Year $2016$

Why do we need rationalisation?

Why do some integrals and derivatives have absolute values?

Problem understanding the concept of a union

Repeated application of L'Hôpital on polynomials doesn't always work?

How is substituting $-y$ for $y$ with $y \neq 0$ legal?

If $\sum_{i = 1}^n a_i b_i = \sum_{i = 1}^n a_i^2 = \sum_{i = 1}^n b_i^2$, then $a_i = b_i$ for all $i$.

Is there a real number which comes just after a particular real number?

Two divergent series such that their product is convergent

Does $1^i$ and $1^{\frac{0}{0}}$ also give $1$ again?

Does $\int_{1}^{\infty} g(x)\ dx$ imply $\lim\limits_{x\to \infty}g(x)=0$?

Convert from base $10$ to base $5$

What is the motivation behind the study of sequences?

quick question on an example of the derivative as a linear map.

To prove the sum is convergent

If $a>b$ then $a^a>b^a. $

Computing two variables limit

What is the difference between identically distributed random variables ?

Calculate the following integral

Why the probability $P(X>Y)$ is the same as $P(\log X > \log Y)$?

Is $|z^2|$ entire function?