User user1337

78 votes

How can I prove that $xy\leq x^2+y^2$?

answered Apr 10, 2013 at 16:45

28 votes

Accepted

Proof: $ \int^{\infty}_{-\infty}\delta(t)^2 dt = 1 ??$

answered Jul 31, 2013 at 9:46

19 votes

Accepted

Is $f(x)= \cos(e^x)$ uniformly continuous?

answered Mar 2, 2013 at 23:09

17 votes

Accepted

Show that there are $ a,b \geq 0 $ so that $ |f(x)| \leq ax+b, \forall x \geq 0.$

answered Feb 26, 2014 at 12:30

15 votes

Can there be a symbol for continuous product?

answered Jul 10, 2017 at 6:09

14 votes

Find the value of $\space\large i^{i^i}$?

answered Jul 9, 2013 at 17:10

13 votes

Prove that the equation $\tan (z)=z$ has only real roots.

answered May 11, 2013 at 18:19

13 votes

$\cos(\arcsin(x)) = \sqrt{1 - x^2}$. How?

answered Mar 28, 2013 at 20:00

12 votes

Theorem 6.20 rudin Integration

answered Dec 5, 2013 at 0:04

12 votes

Accepted

Difference between lim and lim sup?

answered Dec 5, 2013 at 12:25

12 votes

Accepted

Why is $x\log(x)$ convex?

answered Dec 5, 2013 at 17:08

12 votes

Accepted

Ahlfors "Prove the formula of Gauss"

answered Apr 14, 2014 at 5:31

12 votes

Proving that there is a perfect square between $n$ and $2n$

answered Mar 15, 2015 at 13:09

12 votes

Accepted

Solving or approximating infinitely nested integral

answered Feb 26, 2017 at 2:19

10 votes

Accepted

Evaluate $\lim_{x \to 0} \frac{\sin(x³)}{x}$ without L'hopital rule

answered May 18, 2015 at 13:15

10 votes

Accepted

If $u$ is harmonic and bounded in $0 < |z| < \rho$, show that the origin is a removable singularity

answered Aug 3, 2013 at 23:31

10 votes

Accepted

Sum of radicals greater than 1

answered Aug 14, 2013 at 17:43

9 votes

Accepted

General case integral $\int^1_0 f(x) \, f'(1-x) \, dx $

answered Aug 22, 2013 at 21:35

9 votes

What is the value of the integral$\int_{0}^{+\infty} \frac{1-\cos t}{t} \, e^{-t} \, \mathrm{d}t$?

answered Jun 5, 2014 at 14:20

9 votes

Accepted

The set of zeros of a holomorphic function is finite in compact sets

answered Jul 3, 2014 at 5:19

9 votes

$e^z, \ \ z \in \mathbb{C}$ isn't invertible

answered Nov 11, 2013 at 9:10

9 votes

What does $\operatorname{diag}\{ A_1, A_2, \dots, A_N \}$ denote?

answered Jun 14, 2015 at 10:38

8 votes

Limit of $\frac{\sqrt{1-\cos x}}x$ using l'Hôpital

answered Nov 29, 2015 at 10:39

8 votes

Non-ordinary differential equation?

answered Mar 28, 2013 at 23:31

8 votes

Closed-form expression for $\sum_{k=0}^n\binom{n}kk^p$ for integers $n,\,p$

answered Apr 8, 2013 at 21:39

7 votes

Accepted

if $f\left(x+y,\frac{y}{x}\right)= x^2-y^2$ then $f(x,y)=?$

answered Mar 18, 2013 at 20:53

7 votes

How to solve $a\cos^2(\theta) + b \sin^2(\theta) = 0$ for $\theta$

answered Mar 20, 2013 at 15:00

7 votes

Accepted

How to represent $\ln(5-x)$ as a power series?

answered Jun 11, 2014 at 14:38

7 votes

Is the $\lim_{x \to 0} \frac0x$ equal to zero?

answered Apr 17, 2014 at 9:19

7 votes

Accepted

The real equation of a pendulum

answered Jul 6, 2015 at 10:52

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510 Answers

How can I prove that $xy\leq x^2+y^2$?

Proof: $ \int^{\infty}_{-\infty}\delta(t)^2 dt = 1 ??$

Is $f(x)= \cos(e^x)$ uniformly continuous?

Show that there are $ a,b \geq 0 $ so that $ |f(x)| \leq ax+b, \forall x \geq 0.$

Can there be a symbol for continuous product?

Find the value of $\space\large i^{i^i}$?

Prove that the equation $\tan (z)=z$ has only real roots.

$\cos(\arcsin(x)) = \sqrt{1 - x^2}$. How?

Theorem 6.20 rudin Integration

Difference between lim and lim sup?

Why is $x\log(x)$ convex?

Ahlfors "Prove the formula of Gauss"

Proving that there is a perfect square between $n$ and $2n$

Solving or approximating infinitely nested integral

Evaluate $\lim_{x \to 0} \frac{\sin(x³)}{x}$ without L'hopital rule

If $u$ is harmonic and bounded in $0 < |z| < \rho$, show that the origin is a removable singularity

Sum of radicals greater than 1

General case integral $\int^1_0 f(x) \, f'(1-x) \, dx $

What is the value of the integral$\int_{0}^{+\infty} \frac{1-\cos t}{t} \, e^{-t} \, \mathrm{d}t$?

The set of zeros of a holomorphic function is finite in compact sets

$e^z, \ \ z \in \mathbb{C}$ isn't invertible

What does $\operatorname{diag}\{ A_1, A_2, \dots, A_N \}$ denote?

Limit of $\frac{\sqrt{1-\cos x}}x$ using l'Hôpital

Non-ordinary differential equation?

Closed-form expression for $\sum_{k=0}^n\binom{n}kk^p$ for integers $n,\,p$

if $f\left(x+y,\frac{y}{x}\right)= x^2-y^2$ then $f(x,y)=?$

How to solve $a\cos^2(\theta) + b \sin^2(\theta) = 0$ for $\theta$

How to represent $\ln(5-x)$ as a power series?

Is the $\lim_{x \to 0} \frac0x$ equal to zero?

The real equation of a pendulum