User q.Then

19 votes

Accepted

What is range of a matrix?

answered Apr 12, 2017 at 1:01

16 votes

Is $x!-(x-1)!-(x-2)!-...-1!$ always divisible by three?

answered Dec 26, 2016 at 6:29

7 votes

For integer $n>3$, prove that $n^2+(n+1)^2\ne (n+2)^2$

answered Dec 26, 2016 at 16:49

5 votes

What is the general solution to $2 \cos^2 x-\cos x=0$?

answered Jan 3, 2017 at 7:39

5 votes

Accepted

Why is $v/\|v\|$ not a unit vector?

answered Apr 23, 2016 at 17:24

4 votes

Show that all permutation group $S_{n}$ when $n\geq 3$ is not abelian group

answered Dec 13, 2016 at 18:32

3 votes

How can I evaluate $\lim\limits_{x\to0}\frac{\sin x}{\sqrt{x}}$?

answered Dec 11, 2016 at 18:35

3 votes

Pigeonhole Elementary School has 500 students. Show that at least two of them were born on the same day of the year.

answered Dec 11, 2016 at 21:39

3 votes

What the set $I$ of invertible elements in $\mathbb{Z}_{9}$?

answered Apr 17, 2017 at 4:10

3 votes

What is the sum of all the Fibonacci numbers from 1 to infinity.

answered May 3, 2016 at 2:53

2 votes

Linear transformation with respect to bases

answered May 17, 2016 at 22:57

2 votes

proving n linearly independent vectors are generating

answered Apr 17, 2016 at 17:57

2 votes

Accepted

Basis for a Subspace of V

answered Apr 17, 2016 at 17:49

2 votes

When are differentials actually useful?

answered Apr 15, 2016 at 22:18

2 votes

Finding image and kernel of this set

answered Apr 25, 2016 at 14:42

2 votes

Accepted

Find a basis for the given subspace in $\Bbb R^4$

answered Apr 27, 2016 at 3:57

2 votes

How do I find the B matrix of $T_k$

answered Mar 26, 2016 at 6:40

2 votes

Drawbacks on using LU decomposition

answered Mar 26, 2016 at 18:41

2 votes

Understanding of Theorem of Basis

answered Mar 27, 2016 at 19:12

2 votes

Aa student takes a $10$-question true/false exam and guesses. What is the probability that the student answers every question incorrectly?

answered Mar 28, 2016 at 6:34

2 votes

Is it acceptable to use "But" in a proof that doesn't use contradiction?

answered Apr 13, 2016 at 1:13

2 votes

Use the Fermat-Euler Theorem to compute $4^{43}\space\left(\text{mod}\space{15}\right)$ and $2^{51}\space\left(\text{mod}\space {21}\right)$

answered Apr 24, 2017 at 0:53

2 votes

If $a$ is a primitive root modulo $p$, then $(p-1) | ord(a)$ in $\mathbb{Z}/p^e\mathbb{Z}$

answered Apr 9, 2017 at 17:07

2 votes

Prove that $\lim_{x\to {\pi}}\sin{\frac{x}{2}} = 1$

answered Dec 13, 2016 at 20:51

2 votes

Expand a determinant

answered Jan 5, 2017 at 0:11

2 votes

Accepted

Definition about sum of subspaces

answered Dec 27, 2016 at 8:39

2 votes

Find $\frac{dy}{dx}$ at $x=3$

answered Jan 9, 2017 at 23:50

2 votes

Accepted

Proving the existence of a complement subspace $U' \subset V$.

answered Dec 22, 2016 at 0:13

2 votes

Let $x$ be an element of the group $G$. Prove that $x^2 = 1$ if and only if $|x|$ is either $1$ or $2$

answered Dec 26, 2016 at 1:57

1 vote

If $L$ is a linear mapping then $L(0) = 0$

answered Apr 9, 2017 at 6:13

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128 Answers

What is range of a matrix?

Is $x!-(x-1)!-(x-2)!-...-1!$ always divisible by three?

For integer $n>3$, prove that $n^2+(n+1)^2\ne (n+2)^2$

What is the general solution to $2 \cos^2 x-\cos x=0$?

Why is $v/\|v\|$ not a unit vector?

Show that all permutation group $S_{n}$ when $n\geq 3$ is not abelian group

How can I evaluate $\lim\limits_{x\to0}\frac{\sin x}{\sqrt{x}}$?

Pigeonhole Elementary School has 500 students. Show that at least two of them were born on the same day of the year.

What the set $I$ of invertible elements in $\mathbb{Z}_{9}$?

What is the sum of all the Fibonacci numbers from 1 to infinity.

Linear transformation with respect to bases

proving n linearly independent vectors are generating

Basis for a Subspace of V

When are differentials actually useful?

Finding image and kernel of this set

Find a basis for the given subspace in $\Bbb R^4$

How do I find the B matrix of $T_k$

Drawbacks on using LU decomposition

Understanding of Theorem of Basis

Aa student takes a $10$-question true/false exam and guesses. What is the probability that the student answers every question incorrectly?

Is it acceptable to use "But" in a proof that doesn't use contradiction?

Use the Fermat-Euler Theorem to compute $4^{43}\space\left(\text{mod}\space{15}\right)$ and $2^{51}\space\left(\text{mod}\space {21}\right)$

If $a$ is a primitive root modulo $p$, then $(p-1) | ord(a)$ in $\mathbb{Z}/p^e\mathbb{Z}$

Prove that $\lim_{x\to {\pi}}\sin{\frac{x}{2}} = 1$

Expand a determinant

Definition about sum of subspaces

Find $\frac{dy}{dx}$ at $x=3$

Proving the existence of a complement subspace $U' \subset V$.

Let $x$ be an element of the group $G$. Prove that $x^2 = 1$ if and only if $|x|$ is either $1$ or $2$

If $L$ is a linear mapping then $L(0) = 0$