Valent's user avatar
Valent's user avatar
Valent's user avatar
Valent
  • Member for 10 years, 6 months
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  • México
4 votes
Accepted

Proving a set is countably infinite $\left \{q \in \Bbb Q:q=\dfrac{a}{b}\ \text{where $a$ is even and $b$ is odd} \right \}$

4 votes

Why does $r = \cos \theta$ produce a circle?

4 votes

Calculate $\displaystyle \lim_{x \to 0} \frac{\sin(x)}{x + \tan(x)}$ with out derivative?

3 votes

Why $x=\pm1$ is not an asymptote of $\frac{x^3}{x^2+1}$?

3 votes

Divisibility induction proof: $8\mid 7^n+3^n-2$

3 votes

Prove that if $f$ is differentiable at $a$ but $g$ is not, then $f$ + $g$ is not differentiable at $a$.

3 votes

Monotone function

3 votes
Accepted

Is my proof for $\lim_{n\to\infty}\frac3{n+1}$ wrong?

3 votes

An exponential inequallity $2^x > 1-x$

3 votes

Find the nth term of geometric series

3 votes
Accepted

Convergence of sequence of functions $ f_n(x)=\begin{cases} n^{p+1}x & \text{if $0≤x≤1/n$}\\ \frac{1}{x^p} & \text{if $1/n<x≤1$} \end{cases} $

3 votes

How to solve ODE with these values given?

3 votes
Accepted

Riemann-Stieltjes integral of a continuous function w.r.t. a step function

3 votes
Accepted

Inverse triangle inequality on $\mathbb{R}^n$

3 votes
Accepted

Show that vector field is $C^\infty$ and calculate its Jacobian matrix at $(0,1,1)$

2 votes
Accepted

Xn binomial limit to infinity

2 votes

Show that $\|AB\|_p \le \|A\|_p \|B\|_p$

2 votes

How do I show that if $f$ is integrable on $[c,b]$ for all $c \in [a,b]$, then $f$ is integrable on $[a,b]$?

2 votes
Accepted

Is $F(2)-F(-2)$ the same thing as $f(2)-f(-2)$?

2 votes
Accepted

Compute partial derivatives of $\int_0^1|f-p|^2dx $

2 votes

Proof that a sequence $(x_n)_{n \ge 1}$ such that $|x_{n+1} - x_n| < \frac{1}{n}$ converges.

2 votes

Prove that $R_n < M_n < L_n$ ,for right, mid-point and left Riemann sum

2 votes
Accepted

If $m \equiv m'$ mod $n$, then gcd$(m,n) = 1$ $\Longleftrightarrow$ gcd$(m',n) = 1$.

2 votes
Accepted

What values of alpha guarantee the convergence of $\sum _{n=0}^{\infty }\left( \frac {\alpha n} {n+1}\right) ^{n}$?

2 votes

Finding limit of sequence quite hard

2 votes

Find the derivative of an integral with respect to the upper limit

2 votes
Accepted

Inequality using integrals and absolute values

2 votes

"Let" in math texts

2 votes

Show f is continuous on (0, ∞) iff f is continuous at 1 for a defined function.

2 votes
Accepted

Induction: the complement A1 U A2 … U An is the intersection of Ac 1, Ac 2, …, Ac n