user avatar
user avatar
user avatar
Dark
  • Member for 7 years, 4 months
  • Last seen more than 3 years ago
  • France
6 votes

Determine if the following series is convergent or divergent $\sum_{n=1}^{\infty}\frac{ \sin{nx}}{n}$

5 votes
Accepted

Find values of $f'(2)$ for given expression

5 votes
Accepted

How to take the exponential of a non-diagonal matrix

4 votes
Accepted

Matrix with irreducible minimal polynomial gives rise to a field

4 votes

If $f(x) = \frac{\cos x + 5\cos 3x + \cos 5x}{\cos 6x + 6\cos4x + 15\cos2x + 10}$then..

4 votes
Accepted

convergence of $a_n$ knowing that $a_n^n$ converges

4 votes
Accepted

Fourier Series of a sum of two functions

4 votes

Proof that $Cov(aX+b, Y+Z)=aCov(X,Y)+aCov(X,Z)$

3 votes

How to find $E[e^{\lambda X}]$ for a random variable $X$?

3 votes

Suppose $\int_0^9f(t)dt=12$. Then is it true that $\int_0^3f(3x)dx = 12$

3 votes

Showing that this is a martingale.(4.13 in Øksendals SDE)

3 votes

$\det(I+\epsilon V)=1+\operatorname{trace}(V)\epsilon+O(\epsilon^2)$

3 votes
Accepted

Limits at infinity of a function with convergent improper integral

2 votes

Checking linear dependence of two vectors in $\mathbb{R}^4$?

2 votes

Find $I$ in $\frac{\overline{SIX}}{\overline{NINE}}=\frac23$

2 votes

Prove that the derivative of $x^w$ is $w x^{w-1}$ for real $w$

2 votes

Integration problem. Does $\left|\int_0^\infty f(x)dx\right|=0$ imply $f=0$ over $(0,\infty)$?

2 votes
Accepted

When arg max - f(x) = arg min f(x)

2 votes

Proving a set of vectors is independent

2 votes
Accepted

How to use the completeness here

2 votes
Accepted

$(\mathcal L(X,Y),\|\cdot \|)$ is complete if $Y$ is complete.

2 votes
Accepted

If X,Y are both bounded and closed, does this imply that X+Y is bounded and closed?

2 votes
Accepted

Does $\sum_{n=1}^\infty \left(\frac{1}{n} - 1\right)^n$ and $\sum_{n=1}^\infty \left(\frac{1}{n} - 1\right)^{n^2}$ converge?

2 votes

Diagonalisation proof

2 votes
Accepted

What can the operator $T$ be?

2 votes
Accepted

Vector space $V\cong \mathbb R^n$ or $\cong \mathbb C^n$.

2 votes

Prove this for any $k>0$

2 votes

Finding other eigenvalue of matrix given one eigenvalue

2 votes

Determine whether $f''(x)>0$ or not in a given interval

1 vote

Convergence of product of sequences of functions