User Lord Soth

73 votes

Accepted

Is there a slowest rate of divergence of a series?

answered Jul 25, 2013 at 17:17

63 votes

Intuitive proofs that $\lim\limits_{n\to\infty}\left(1+\frac xn\right)^n=e^x$

answered Apr 18, 2013 at 0:13

21 votes

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Derivative of function is bigger??!

answered Aug 16, 2013 at 19:00

19 votes

What if $\pi$ was an algebraic number? (significance of algebraic numbers)

answered Aug 16, 2013 at 0:49

16 votes

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Proof that any square is of the form $3k$ or $3k+1$

answered Apr 1, 2014 at 20:45

14 votes

Solutions to $a+b+c=12$, $a, b, c \in \mathbb{N}_0$

answered Jun 29, 2013 at 19:26

12 votes

Accepted

Formula for the $1\cdot 2 + 2\cdot 3 + 3\cdot 4+\ldots + n\cdot (n+1)$ sum

answered Mar 31, 2013 at 20:32

12 votes

pandigital rational approximations to the golden ratio and the base of the natural logarithm

answered Jul 23, 2013 at 0:12

11 votes

Accepted

Where did this statistics formula come from: $E[X^2] = \mu^2 + \sigma^2$

answered Aug 6, 2013 at 18:35

11 votes

Accepted

Find $a\in\mathbb{N}$ such that $n^4+a$ is not prime $\forall n\in\mathbb{N}$

answered Oct 27, 2013 at 17:38

11 votes

Find the last two digits of $ 7^{81} ?$

answered Apr 15, 2013 at 5:02

11 votes

Best way to express 2014

answered Mar 7, 2014 at 18:53

10 votes

Show that the identity matrix $I$ must have norm $1$.

answered Apr 17, 2013 at 22:54

10 votes

Find the next number in the sequence

answered Aug 20, 2013 at 19:52

9 votes

Find the sum : $\sin^{-1}\frac{1}{\sqrt{2}}+\sin^{-1}\frac{\sqrt{2}-1}{\sqrt{6}}+\sin^{-1}\frac{\sqrt{3}-\sqrt{2}}{\sqrt{12}}+\cdots$

answered Jul 29, 2013 at 3:12

9 votes

Accepted

Is there a prime number ending with the natural number $n$

answered Sep 10, 2014 at 22:07

8 votes

Accepted

Find a real $2\times 2$ matrix $A$ (other than $A = I$ ) such that $A^5 = I $.

answered Jan 26, 2014 at 23:41

7 votes

Proving $\big(n!^{\frac1n}\big)_{n\in\mathbb N^*} \to \infty$

answered Mar 29, 2014 at 1:26

7 votes

Accepted

Proving that $-\frac{\cos x +\cos^2 x + \sin^2 x}{(1 + \cos x)^2} = -\frac{1}{1 + \cos x}$

answered Apr 3, 2014 at 19:18

7 votes

Accepted

How do I solve $\; 3^{2x+1}-10\cdot 3^x+3=0 \quad?$

answered Jul 1, 2013 at 18:19

7 votes

Finding the limit of roots products $(\sqrt{2}-\sqrt[3]{2})(\sqrt{2}-\sqrt[4]{2})(\sqrt{2}-\sqrt[5]{2})\cdot \cdot \cdot (\sqrt{2}-\sqrt[n]{2})$

answered Jul 25, 2013 at 19:03

7 votes

Finding squared norm of vector

answered Apr 19, 2013 at 1:16

6 votes

Ways to fill a $n\times n$ square with $1\times 1$ squares and $1\times 2$ rectangles

answered Apr 11, 2013 at 21:45

6 votes

Accepted

Evaluate $\lim_{x \to 0} \frac{1-\cos(\sin(4x))}{\sin^2(\sin(3x))}$ without L'Hospital

answered Nov 6, 2013 at 0:55

6 votes

Find the determinant by using elementary row operations

answered Jul 1, 2013 at 18:50

6 votes

Uses of the incidence matrix of a graph

answered Jul 4, 2013 at 17:08

6 votes

How can I, as a future mathematician, contribute most to Smart Grid research?

answered Jul 12, 2013 at 16:54

6 votes

Accepted

Can anyone give me x,y coordinates for an octagon?

answered Sep 10, 2014 at 1:49

6 votes

Accepted

Evaluating $\int_{\pi/3}^{\pi/2}\frac{1}{\sin\left(x\right)-\cos\left(x\right)+1} \operatorname dx$

answered Jan 26, 2014 at 23:55

6 votes

If $(a-1),a,(a+1)$ are consecutive positive integers, $ (a+1)^3 \neq a^3 + (a-1)^3$

answered Mar 6, 2014 at 2:44

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199 Answers

Is there a slowest rate of divergence of a series?

Intuitive proofs that $\lim\limits_{n\to\infty}\left(1+\frac xn\right)^n=e^x$

Derivative of function is bigger??!

What if $\pi$ was an algebraic number? (significance of algebraic numbers)

Proof that any square is of the form $3k$ or $3k+1$

Solutions to $a+b+c=12$, $a, b, c \in \mathbb{N}_0$

Formula for the $1\cdot 2 + 2\cdot 3 + 3\cdot 4+\ldots + n\cdot (n+1)$ sum

pandigital rational approximations to the golden ratio and the base of the natural logarithm

Where did this statistics formula come from: $E[X^2] = \mu^2 + \sigma^2$

Find $a\in\mathbb{N}$ such that $n^4+a$ is not prime $\forall n\in\mathbb{N}$

Find the last two digits of $ 7^{81} ?$

Best way to express 2014

Show that the identity matrix $I$ must have norm $1$.

Find the next number in the sequence

Find the sum : $\sin^{-1}\frac{1}{\sqrt{2}}+\sin^{-1}\frac{\sqrt{2}-1}{\sqrt{6}}+\sin^{-1}\frac{\sqrt{3}-\sqrt{2}}{\sqrt{12}}+\cdots$

Is there a prime number ending with the natural number $n$

Find a real $2\times 2$ matrix $A$ (other than $A = I$ ) such that $A^5 = I $.

Proving $\big(n!^{\frac1n}\big)_{n\in\mathbb N^*} \to \infty$

Proving that $-\frac{\cos x +\cos^2 x + \sin^2 x}{(1 + \cos x)^2} = -\frac{1}{1 + \cos x}$

How do I solve $\; 3^{2x+1}-10\cdot 3^x+3=0 \quad?$

Finding the limit of roots products $(\sqrt{2}-\sqrt[3]{2})(\sqrt{2}-\sqrt[4]{2})(\sqrt{2}-\sqrt[5]{2})\cdot \cdot \cdot (\sqrt{2}-\sqrt[n]{2})$

Finding squared norm of vector

Ways to fill a $n\times n$ square with $1\times 1$ squares and $1\times 2$ rectangles

Evaluate $\lim_{x \to 0} \frac{1-\cos(\sin(4x))}{\sin^2(\sin(3x))}$ without L'Hospital

Find the determinant by using elementary row operations

Uses of the incidence matrix of a graph

How can I, as a future mathematician, contribute most to Smart Grid research?

Can anyone give me x,y coordinates for an octagon?

Evaluating $\int_{\pi/3}^{\pi/2}\frac{1}{\sin\left(x\right)-\cos\left(x\right)+1} \operatorname dx$

If $(a-1),a,(a+1)$ are consecutive positive integers, $ (a+1)^3 \neq a^3 + (a-1)^3$