User peter.petrov

25 votes

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What is wrong with this argument that closed interval [0, 1] is not compact?

answered Mar 10, 2016 at 12:10

23 votes

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Normalizing a quaternion

answered Mar 18, 2016 at 19:13

15 votes

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If $ab=ba$, Prove $a^2$ commutes with $b^2$

answered May 14, 2015 at 14:59

12 votes

So what really is a random variable?

answered Aug 2, 2020 at 20:04

11 votes

What number follows immediately after a rational number?

answered Jul 11, 2020 at 11:09

9 votes

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Showing planarity of graphs

answered May 15, 2015 at 13:23

9 votes

How can a square root be defined since it has two answers?

answered Feb 29, 2016 at 22:41

8 votes

Solve the system of equations $x+2^x=y+2^y$ and $x^2+xy+y^2=12$

answered May 9, 2016 at 13:47

8 votes

Determining the closed form of $\sum\limits_{r = 2}^n \binom{n}{r} \binom{r}{2}$

answered Jun 30, 2020 at 11:14

7 votes

The number of real roots of $x^5 + 2x^3 + x^2 + 2 = 0 $ is

answered Mar 16, 2016 at 19:01

7 votes

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Difference between a limit and accumulation point?

answered Feb 3, 2016 at 15:05

7 votes

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How can I improve creative thinking in Math?

answered Apr 27, 2021 at 20:49

6 votes

Important Trigonometric Angles 's Values To Remember For IIT-JEE?

answered Jul 6, 2020 at 10:57

6 votes

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Show that $x^2+y^2 = 3$ has no rational solutions

answered Aug 28, 2020 at 9:04

6 votes

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Proving equality - a sum including binomial coefficient $\sum_{k=1}^{n}k{n \choose k}2^{n-k}=n3^{n-1}$

answered Feb 15, 2016 at 12:43

6 votes

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Number of $60$th primitive roots of $-1$

answered Jul 20, 2015 at 20:33

6 votes

Will these frogs ever meet?

answered Oct 26, 2015 at 16:09

6 votes

prove $\max\{x,y\} = (x+y+|x - y|)/2$

answered Apr 11, 2016 at 20:40

5 votes

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Solve for $x$ for the following exponential equation $2^{2x+1} = 3^{2x+1}$. What am I doing wrong?

answered Apr 3, 2016 at 21:35

5 votes

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How to integrate $\int_{-\infty}^{\infty} xe^{-2\lambda |x|} dx$?

answered Jun 27, 2020 at 10:45

5 votes

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Cantor Set ternary representation

answered Jul 19, 2016 at 13:59

5 votes

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Explain how can we graph the equation $y+|y|=x+|x|$.( Relation involving absolute values)

answered Apr 8, 2020 at 9:36

5 votes

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Using two dimensional mathematical induction

answered May 15, 2015 at 21:38

5 votes

Spivak - Chapter 7 Question 5 - Could f(x) be a function other than a constant function?

answered Apr 1, 2015 at 22:03

5 votes

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$a \Rightarrow b$, $b \Rightarrow c$, $c \Rightarrow d$, $d \Rightarrow a$. Argue that any two of these statements are logically equivalent.

answered Feb 10, 2016 at 23:04

5 votes

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How to use Pigeon Hole Principle here?

answered Sep 29, 2020 at 16:11

5 votes

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Solve the inequality $x^4-3x^2+5\ge0$

answered Oct 21, 2020 at 15:29

5 votes

Recurrence without intuitive leaps

answered Oct 22, 2020 at 23:41

5 votes

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Area of a Semi-Regular Decagon

answered Jan 19, 2021 at 14:26

4 votes

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Example of Devil's nested radicals

answered Jul 2, 2020 at 9:59

Stack Exchange Network

411 Answers

What is wrong with this argument that closed interval [0, 1] is not compact?

Normalizing a quaternion

If $ab=ba$, Prove $a^2$ commutes with $b^2$

So what really is a random variable?

What number follows immediately after a rational number?

Showing planarity of graphs

How can a square root be defined since it has two answers?

Solve the system of equations $x+2^x=y+2^y$ and $x^2+xy+y^2=12$

Determining the closed form of $\sum\limits_{r = 2}^n \binom{n}{r} \binom{r}{2}$

The number of real roots of $x^5 + 2x^3 + x^2 + 2 = 0 $ is

Difference between a limit and accumulation point?

How can I improve creative thinking in Math?

Important Trigonometric Angles 's Values To Remember For IIT-JEE?

Show that $x^2+y^2 = 3$ has no rational solutions

Proving equality - a sum including binomial coefficient $\sum_{k=1}^{n}k{n \choose k}2^{n-k}=n3^{n-1}$

Number of $60$th primitive roots of $-1$

Will these frogs ever meet?

prove $\max\{x,y\} = (x+y+|x - y|)/2$

Solve for $x$ for the following exponential equation $2^{2x+1} = 3^{2x+1}$. What am I doing wrong?

How to integrate $\int_{-\infty}^{\infty} xe^{-2\lambda |x|} dx$?

Cantor Set ternary representation

Explain how can we graph the equation $y+|y|=x+|x|$.( Relation involving absolute values)

Using two dimensional mathematical induction

Spivak - Chapter 7 Question 5 - Could f(x) be a function other than a constant function?

$a \Rightarrow b$, $b \Rightarrow c$, $c \Rightarrow d$, $d \Rightarrow a$. Argue that any two of these statements are logically equivalent.

How to use Pigeon Hole Principle here?

Solve the inequality $x^4-3x^2+5\ge0$

Recurrence without intuitive leaps

Area of a Semi-Regular Decagon

Example of Devil's nested radicals