User Klaus Draeger

15 votes

How to prove that the Fibonacci sequence is periodic mod 5 without using induction?

answered Jul 12, 2015 at 12:30

5 votes

Giving a specific example of a positive sequence increasing to 1 and with its partial products having a positive limit

answered Apr 16, 2016 at 23:02

4 votes

Accepted

If $G = \{a + b: a, b \in A\}$ a group, then is $A$ a group?

answered Jan 13, 2016 at 20:18

4 votes

Accepted

Proof of 3-chain subsequence problem from assignment 2 of MIT OCW 6.042

answered Nov 6, 2014 at 14:19

3 votes

Accepted

Does $k\cdot x < y$ imply that $x \ne y$?

answered Jul 10, 2015 at 13:19

2 votes

How do you create an alternating series with the sign being the same twice in a row?

answered Apr 17, 2016 at 1:45

2 votes

Determinant of Adjacency Matrix is null

answered Nov 8, 2015 at 12:04

2 votes

How do you compute eigenvalues/vectors of big $n\times n$ matrix?

answered Dec 16, 2015 at 13:09

2 votes

To prove a sequence is Cauchy

answered Jun 25, 2015 at 11:26

2 votes

If $\frac{a}{b}<\frac{c}{d}$ and $\frac{e}{f}<\frac{g}{h}$, then $\frac{a+e}{b+f} < \frac{c+g}{d+h}$.

answered Jul 9, 2015 at 14:16

2 votes

Accepted

Why this matrix is not a distance matrix?

answered Jul 10, 2015 at 12:23

2 votes

Accepted

Recursive definition of a set of strings.

answered Feb 18, 2015 at 14:47

2 votes

Accepted

expressing inclusive OR using exclusive OR.

answered Jul 23, 2015 at 12:22

2 votes

show that in a group of five people (where any two people are either friends or enemies)...

answered Aug 6, 2015 at 22:30

2 votes

Accepted

After how many days did Akbar join Ajay given the following conditions.

answered Sep 13, 2015 at 20:23

1 vote

Find the remainder when $21^3$ +$23^3$+$25^3$+$27^3$ is divided by $96$?

answered Nov 2, 2015 at 13:03

1 vote

If $ab(a+b)=2$ then what will be the value of $\frac{1}{(ab)^3}-a^3-b^3$?

answered Aug 6, 2015 at 15:29

1 vote

Why does = change to $\leq$ and then to = in this proof of |a+b| = |a|+|b|?

answered Mar 5, 2015 at 13:20

1 vote

Accepted

Prove that regular languages are closed under operation

answered May 1, 2015 at 11:51

1 vote

6 lamp at the circumcircle

answered Jan 16, 2015 at 14:58

1 vote

Accepted

Can't solve this exercise

answered Jan 3, 2016 at 13:24

1 vote

Accepted

Finding the Dimension of a given space $V$

answered Apr 12, 2016 at 18:32

1 vote

How to prove $\gcd(a,b) \cdot \gcd(c,d)=\gcd(ac,ad,bc,bd)$?

answered Apr 8, 2017 at 20:55

0 votes

How can I calculate the dot product of two vectors if I know both dot products with a third vector?

answered Feb 23, 2018 at 13:24

0 votes

Function to express a time interval with results between 0 and 1

answered Jun 5, 2015 at 12:01

0 votes

$|\mathbb N^{\mathbb N}| = |2^\mathbb N|$ by finding a bijection

answered Jul 14, 2015 at 18:22

0 votes

Accepted

Example of an unbounded sequence whose convergent subsequences converge to same limit

answered Nov 3, 2015 at 13:43

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27 Answers

How to prove that the Fibonacci sequence is periodic mod 5 without using induction?

Giving a specific example of a positive sequence increasing to 1 and with its partial products having a positive limit

If $G = \{a + b: a, b \in A\}$ a group, then is $A$ a group?

Proof of 3-chain subsequence problem from assignment 2 of MIT OCW 6.042

Does $k\cdot x < y$ imply that $x \ne y$?

How do you create an alternating series with the sign being the same twice in a row?

Determinant of Adjacency Matrix is null

How do you compute eigenvalues/vectors of big $n\times n$ matrix?

To prove a sequence is Cauchy

If $\frac{a}{b}<\frac{c}{d}$ and $\frac{e}{f}<\frac{g}{h}$, then $\frac{a+e}{b+f} < \frac{c+g}{d+h}$.

Why this matrix is not a distance matrix?

Recursive definition of a set of strings.

expressing inclusive OR using exclusive OR.

show that in a group of five people (where any two people are either friends or enemies)...

After how many days did Akbar join Ajay given the following conditions.

Find the remainder when $21^3$ +$23^3$+$25^3$+$27^3$ is divided by $96$?

If $ab(a+b)=2$ then what will be the value of $\frac{1}{(ab)^3}-a^3-b^3$?

Why does = change to $\leq$ and then to = in this proof of |a+b| = |a|+|b|?

Prove that regular languages are closed under operation

6 lamp at the circumcircle

Can't solve this exercise

Finding the Dimension of a given space $V$

How to prove $\gcd(a,b) \cdot \gcd(c,d)=\gcd(ac,ad,bc,bd)$?

How can I calculate the dot product of two vectors if I know both dot products with a third vector?

Function to express a time interval with results between 0 and 1

$|\mathbb N^{\mathbb N}| = |2^\mathbb N|$ by finding a bijection

Example of an unbounded sequence whose convergent subsequences converge to same limit