User user121418 - Mathematics Stack Exchange

user121418

Member for 9 years, 8 months
Last seen more than 9 years ago

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16 Questions

Score Activity Newest Views

6 votes

3 answers

5k views

If $N$ is a normal subgroup of a group $G$, and $M$ is a characteristic subgroup of $N$, then $M$ is a normal subgroup of $G$.

asked Jan 22, 2014 at 3:18

9 votes

3 answers

1k views

For continuous function $ f:\mathbb S^1 \to \mathbb R$ there exists uncountably many distinct points $x,y$ such that $f(x)=f(y)$

asked Jan 16, 2014 at 1:37

4 votes

1 answer

1k views

The distance function on a metric space

asked Jan 15, 2014 at 2:24

8 votes

1 answer

150 views

Find $\lim_{n\to\infty}\int_{-\pi}^{\pi}f(t)\cos^2(nt) \,dt$

asked Jan 21, 2014 at 2:19

-1 votes

1 answer

57 views

$\lim_{n\to\infty}((\sum_{r=1}^{k}(n+r)^m/n^{m-1})-kn)$ where $m,k > 0$ are fixed integers

asked Jan 25, 2014 at 16:29

4 votes

3 answers

848 views

Find the largest interval for which the following series is convergent at all points x in it

asked Jan 25, 2014 at 14:09

1 vote

2 answers

284 views

Let $f:(0,1)→R$ be continuous. Pick out the statements which imply that $f$ is uniformly continuous.

asked Jan 22, 2014 at 8:37

7 votes

1 answer

863 views

Does there exist any continuous but not uniformly continuous function $f(x)$ such that $\sin(f(x))$ is uniformly continuous?

asked Jan 23, 2014 at 8:52

2 votes

3 answers

343 views

Fixed point and period of continuous function

asked Jan 22, 2014 at 13:20

6 votes

3 answers

168 views

Can the following integral be computed?

asked Jan 22, 2014 at 5:15

1 vote

2 answers

334 views

If $\sum n^2 a_n^2<\infty$ then $\sum a_n$ is convergent. [duplicate]

asked Jan 22, 2014 at 8:12

1 vote

1 answer

997 views

Which of the following form an ideal in this ring?

asked Jan 20, 2014 at 2:36

1 vote

1 answer

124 views

eigen value problem of the following matrix [duplicate]

asked Jan 19, 2014 at 1:58

1 vote

2 answers

168 views

trouble calculating sum of the series $ \sum\left(\frac{n^2}{2^n}\right) $

asked Jan 19, 2014 at 0:43

1 vote

1 answer

125 views

Is there any relation between Minimal polynomial of a matrix in M(n,C) and its diagonalizablity?

asked Jan 18, 2014 at 20:00

2 votes

1 answer

793 views

Is the set of all matrices in M(n;R) all of whose eigenvalues satisfy the condition |λ|≤2. compact?

asked Jan 15, 2014 at 1:46