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Alberto Debernardi
  • Member for 8 years, 2 months
  • Last seen more than a month ago
  • Sabadell
20 votes

How do I square a logarithm?

18 votes
Accepted

Squaring a trigonometric inequality

18 votes
Accepted

If $\sum a_n$ is convergent, is $\sum\frac{a_n}{n}$ absolutely convergent?

9 votes
Accepted

almost everywhere Vs. almost sure

8 votes

Prove $1+2\sqrt3$ is not a rational number

7 votes

$\lim_{n\rightarrow\infty}\frac{1}{n}\sum_{k=1}^{n}\frac{k}{k^{2}+1}$

5 votes

Rephrasing the definition of a limit

5 votes
Accepted

Prove that limit doesn’t exist anywhere?

5 votes

Does this sum converge, is my solution good?

5 votes

Evaluating the integral $\int_0^\infty \frac{\sin x} x \,\mathrm dx = \frac \pi 2$?

5 votes
Accepted

If $f:[a,b]\rightarrow \mathbb{R}$ is continuous on $[a,b]$ and $f(a)\neq f(b)$, then $f$ is stricly monotonic on some segment $[c,d]\subseteq [a,b]$?

4 votes
Accepted

Summation. Combining different set of indices.

4 votes
Accepted

Two non-negative functions $\,f,g$, such that $\,f \not\in \mathcal O(g)$ and $ g \not\in \mathcal O(\,f)$

4 votes

Prove that $\overline{A \cap B} = \overline{A} \cup \overline{B}$

4 votes

How to prove that this sequence converges? $\sum_{n=1}^{\infty} \frac{1}{n\ln^2(n)}$

4 votes

Show integral limit

3 votes

Determine if a series defined by cases is convergent and calculate the sum

3 votes
Accepted

Optimization of $e^{x^2 + y}$ on $x+y \leq 2$

3 votes

How to know if equation can be solved by factorising before trying?

3 votes
Accepted

Determining Bounded Variation

3 votes
Accepted

Prove $\{n^2\}_{n=1}^{\infty}$ is not convergent

3 votes
Accepted

Divergence of Fourier series

3 votes

When does the curve $y = {x^p}\cos \frac{\pi }{x}(0 < x \leqslant 1)$ have finite length?

3 votes

$\sum a_n$ converges, converge $\sum (a_n)/(1-a_n)$ too?

3 votes

Correct mathematical expression

2 votes

Proof that the series $1 * 1 + 2 * 2 + 3 * 3 ... n * n$ is $O(n^3)$

2 votes

How to not feel bad for doing math?

2 votes
Accepted

Is it true that when $r=s-1$ is summed from $0\to k$, then $s$ is summed from $1\to k+1$?

2 votes
Accepted

Question regarding matrices and determinants.

2 votes
Accepted

How do I remove this product?