User jim

24 votes

Are normal subgroups transitive?

answered Dec 10, 2012 at 7:56

19 votes

Prove that $x = 2$ is the unique solution to $3^x + 4^x = 5^x$ where $x \in \mathbb{R}$

answered Jan 7, 2013 at 13:19

13 votes

Solve equations $\sqrt{t +9} - \sqrt{t} = 1$

answered May 22, 2013 at 13:03

11 votes

Closed subsets $A,B\subset\mathbb{R}^2$ so that $A+B$ is not closed

answered Oct 18, 2012 at 14:58

8 votes

What are the strategies I can use to prove $f^{-1}(S \cap T) = f^{-1}(S) \cap f^{-1}(T)$?

answered Nov 4, 2012 at 6:15

8 votes

Accepted

What Möbius transformation maps the unit circle $\{z: |z|=1\}$ to the real axis?

answered Mar 19, 2013 at 14:32

7 votes

Accepted

Prove or disprove: If $x^T A x = 0 $ for all $x$, then $ A = 0 $.

answered Mar 15, 2013 at 16:29

5 votes

Accepted

If $f(x+y)=f(x)\cdot f(y)$, then $f(x)=e^{ax}$

answered Feb 8, 2013 at 7:44

5 votes

Accepted

$(n-1)$-dimensional subspace of an $n$-dimensional vector space

answered Feb 22, 2013 at 14:01

5 votes

Accepted

find the number of limit points of the set{$ \frac{1}{m} +\frac{1}{n}:m,n \in \Bbb N$}

answered Sep 18, 2013 at 12:07

5 votes

Accepted

uniform continuity and which of the following statements are true??(NBHM-$2014$)

answered Jan 26, 2014 at 6:03

5 votes

Accepted

Sylow p-subgroup of $GL_n(F_p)$

answered Nov 12, 2012 at 6:26

5 votes

Proving that the matrix is not invertible.

answered Nov 23, 2012 at 12:11

4 votes

Pick out the case(s) which ensure that the polynomial $p(\cdot)$ has a root in the interval $[0, 1]$

answered Jan 4, 2013 at 14:29

4 votes

Accepted

What are $2222^{5555}+5555^{2222} \pmod 7$ and $9^{2n+1}+8^{n+2} \pmod{73}$?

answered Nov 29, 2012 at 11:53

4 votes

Accepted

Modulo Theorem proof

answered Nov 29, 2012 at 11:38

4 votes

Accepted

Invert of Matrix I-BA

answered Mar 7, 2013 at 6:39

3 votes

Accepted

Proving G is commutative.

answered Feb 26, 2013 at 1:54

3 votes

Accepted

How does one find this matrix $A$?

answered Feb 20, 2013 at 4:18

3 votes

Value of $ \sum \limits_{k=1}^{81} \frac{1}{\sqrt{k} + \sqrt{k+1}} = \frac{1}{\sqrt{1} + \sqrt{2}} + \cdots + \frac{1}{\sqrt{80} + \sqrt{81}} $?

answered Feb 22, 2013 at 6:42

3 votes

product of two uniformly continuous functions is uniformly continuous

answered Mar 29, 2013 at 7:07

3 votes

Prove with integration the inequality $e(\frac{n}{e})^n < n! < n \times e(\frac{n}{e})^n$

answered May 23, 2013 at 7:20

3 votes

Spliting Field over $\mathbb{F}_3$

answered May 29, 2013 at 11:55

3 votes

Accepted

Similar Matrices in Subfields

answered Dec 13, 2012 at 12:11

3 votes

Prove that $f$ is uniform continuous

answered Jan 30, 2013 at 14:12

2 votes

Accepted

group of order $198$

answered Jan 23, 2013 at 11:43

2 votes

Calculate the rank of matrix $B-C$ while $AB=AC$ and $\operatorname{rank}(A) = r$?

answered Dec 1, 2012 at 12:18

2 votes

Proof that $(a,b)\not\cong[a,b]$

answered Oct 13, 2012 at 12:20

2 votes

Trouble understanding equivalence relations and equivalence classes...anyone care to explain?

answered Nov 13, 2012 at 9:21

2 votes

Accepted

Suppose $f:[a,b] \rightarrow \mathbb{R}$ is bounded and continuous at all points except $c$ where $a < c <b$. Prove that $f$ is Riemann integrable.

answered Nov 27, 2012 at 6:03

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64 Answers

Are normal subgroups transitive?

Prove that $x = 2$ is the unique solution to $3^x + 4^x = 5^x$ where $x \in \mathbb{R}$

Solve equations $\sqrt{t +9} - \sqrt{t} = 1$

Closed subsets $A,B\subset\mathbb{R}^2$ so that $A+B$ is not closed

What are the strategies I can use to prove $f^{-1}(S \cap T) = f^{-1}(S) \cap f^{-1}(T)$?

What Möbius transformation maps the unit circle $\{z: |z|=1\}$ to the real axis?

Prove or disprove: If $x^T A x = 0 $ for all $x$, then $ A = 0 $.

If $f(x+y)=f(x)\cdot f(y)$, then $f(x)=e^{ax}$

$(n-1)$-dimensional subspace of an $n$-dimensional vector space

find the number of limit points of the set{$ \frac{1}{m} +\frac{1}{n}:m,n \in \Bbb N$}

uniform continuity and which of the following statements are true??(NBHM-$2014$)

Sylow p-subgroup of $GL_n(F_p)$

Proving that the matrix is not invertible.

Pick out the case(s) which ensure that the polynomial $p(\cdot)$ has a root in the interval $[0, 1]$

What are $2222^{5555}+5555^{2222} \pmod 7$ and $9^{2n+1}+8^{n+2} \pmod{73}$?

Modulo Theorem proof

Invert of Matrix I-BA

Proving G is commutative.

How does one find this matrix $A$?

Value of $ \sum \limits_{k=1}^{81} \frac{1}{\sqrt{k} + \sqrt{k+1}} = \frac{1}{\sqrt{1} + \sqrt{2}} + \cdots + \frac{1}{\sqrt{80} + \sqrt{81}} $?

product of two uniformly continuous functions is uniformly continuous

Prove with integration the inequality $e(\frac{n}{e})^n < n! < n \times e(\frac{n}{e})^n$

Spliting Field over $\mathbb{F}_3$

Similar Matrices in Subfields

Prove that $f$ is uniform continuous

group of order $198$

Calculate the rank of matrix $B-C$ while $AB=AC$ and $\operatorname{rank}(A) = r$?

Proof that $(a,b)\not\cong[a,b]$

Trouble understanding equivalence relations and equivalence classes...anyone care to explain?

Suppose $f:[a,b] \rightarrow \mathbb{R}$ is bounded and continuous at all points except $c$ where $a < c <b$. Prove that $f$ is Riemann integrable.