User Derek Luna

5 votes

Inequality proof by induction

answered Nov 20, 2020 at 2:41

5 votes

Accepted

If $A$ and $B$ are sets, do $\mathcal{P}(A - B)$ and $\mathcal{P}(A) - \mathcal{P}(B)$ equal?

answered Jan 9, 2021 at 7:25

4 votes

Accepted

Find all the integer solutions of $x^2-4y^2=1$

answered Jan 5, 2021 at 9:00

4 votes

How to prove that, if two numbers are equal $\mod2$ and$\mod3$ ,they are equal$\mod 6 $?

answered Nov 9, 2020 at 11:14

4 votes

Accepted

If the square of an irrational number r is irrational, can it be equal to a + br, where both a and b are rational

answered Nov 10, 2020 at 4:37

3 votes

Why is my solution wrong to $\,99x \equiv 18 \mod 30$

answered Nov 16, 2020 at 14:30

3 votes

Accepted

construct a sequence Sn that does not converge but its arithmetic mean converges to 0

answered Nov 4, 2020 at 11:11

3 votes

Accepted

What is the connection between number of permutations and number of subsets?

answered Sep 7, 2019 at 5:22

3 votes

Accepted

(2n + 1) + (2n) is odd?

answered Dec 2, 2020 at 11:26

3 votes

Accepted

Prove that all members of a recursive sequence are coprime

answered Jan 6, 2021 at 12:13

3 votes

How to verify if vectors of $\mathbb{R}^{2 \times 2}$ span $\mathbb{R}^{2 \times 2}$

answered Feb 9, 2021 at 20:09

2 votes

Prove that Dirichlet function is non monotonic.

answered Jan 13, 2021 at 13:03

2 votes

Prove prime number p divides 1+...+n^{p-2}

answered Feb 2, 2021 at 18:15

2 votes

Accepted

Let $(G,*)$ be an abelian group. Prove that, for all $a,b \in G$, then $(ab)^n = a^nb^n$ for three consecutive integers $n$.

answered Jan 13, 2021 at 10:08

2 votes

Proof of $(ab)^{-1} = a^{-1}b^{-1}$

answered Jan 13, 2021 at 22:36

2 votes

Accepted

Proving that $\gcd(a,ak+c)=\gcd(a,c)$

answered Jan 14, 2021 at 19:46

2 votes

Accepted

Disproving that $\mathbb N$ is a complete Set

answered Jan 6, 2021 at 10:54

2 votes

What functions have $f (t + 1)=f (t)+ 2$?

answered Jan 9, 2021 at 6:31

2 votes

Find the function p(x)

answered Jan 10, 2021 at 0:11

2 votes

Cannot find limit using epsilon delta definition

answered Dec 26, 2020 at 4:27

2 votes

Accepted

probability of selecting two roses of different colors when two roses are drawn at random from $2$ red roses, $4$ yellow roses and $6$ pink roses

answered Dec 28, 2020 at 5:26

2 votes

Accepted

Show that 2020 divides $p\left( n \right)$ for every integer $n$

answered Nov 21, 2020 at 5:49

2 votes

Proving a sequence has a finite Limit

answered Nov 25, 2020 at 21:04

2 votes

Accepted

If $\gcd (a,n) = 1$, how can we prove that $\gcd(a + kn, n) = 1$?

answered Nov 26, 2020 at 19:15

2 votes

Accepted

Show that $4\mid f_n$ if and only if $6\mid n$.

answered Nov 26, 2020 at 20:06

2 votes

Accepted

Solve this logic problem, or justify why it can't be solved?

answered Nov 20, 2020 at 11:43

2 votes

Accepted

How do you find a defined relation?

answered Apr 21, 2019 at 5:33

2 votes

Accepted

Why are permutations defined as bijective?

answered Apr 7, 2019 at 16:13

2 votes

Proposition: Al knows only Bill

answered Oct 17, 2019 at 4:58

2 votes

If $a+b\equiv 0 \mod 2$ then $a,b$ are both odd or even by using contrapositive.

answered Apr 3, 2020 at 8:59

Stack Exchange Network

159 Answers

Inequality proof by induction

If $A$ and $B$ are sets, do $\mathcal{P}(A - B)$ and $\mathcal{P}(A) - \mathcal{P}(B)$ equal?

Find all the integer solutions of $x^2-4y^2=1$

How to prove that, if two numbers are equal $\mod2$ and$\mod3$ ,they are equal$\mod 6 $?

If the square of an irrational number r is irrational, can it be equal to a + br, where both a and b are rational

Why is my solution wrong to $\,99x \equiv 18 \mod 30$

construct a sequence Sn that does not converge but its arithmetic mean converges to 0

What is the connection between number of permutations and number of subsets?

(2n + 1) + (2n) is odd?

Prove that all members of a recursive sequence are coprime

How to verify if vectors of $\mathbb{R}^{2 \times 2}$ span $\mathbb{R}^{2 \times 2}$

Prove that Dirichlet function is non monotonic.

Prove prime number p divides 1+...+n^{p-2}

Let $(G,*)$ be an abelian group. Prove that, for all $a,b \in G$, then $(ab)^n = a^nb^n$ for three consecutive integers $n$.

Proof of $(ab)^{-1} = a^{-1}b^{-1}$

Proving that $\gcd(a,ak+c)=\gcd(a,c)$

Disproving that $\mathbb N$ is a complete Set

What functions have $f (t + 1)=f (t)+ 2$?

Find the function p(x)

Cannot find limit using epsilon delta definition

probability of selecting two roses of different colors when two roses are drawn at random from $2$ red roses, $4$ yellow roses and $6$ pink roses

Show that 2020 divides $p\left( n \right)$ for every integer $n$

Proving a sequence has a finite Limit

If $\gcd (a,n) = 1$, how can we prove that $\gcd(a + kn, n) = 1$?

Show that $4\mid f_n$ if and only if $6\mid n$.

Solve this logic problem, or justify why it can't be solved?

How do you find a defined relation?

Why are permutations defined as bijective?

Proposition: Al knows only Bill

If $a+b\equiv 0 \mod 2$ then $a,b$ are both odd or even by using contrapositive.