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WhatsUp
  • Member for 8 years, 10 months
  • Last seen more than a week ago
19 votes
Accepted

Prove that $x$ is an integer if $x^4-x$ and $x^3-x$ are integers.

19 votes

What is the meaning of the ideal class group?

14 votes
Accepted

Evaluate $\lim\limits_{n \to \infty}\frac{(-1)^n}{n!}\int_0^n (x-1)(x-2)\cdots(x-n){\rm d}x$

14 votes

Cut a ribbon with a minumum amount of cuts (Middle School Math)

12 votes

End(M) for cyclic R-module M is a commutative ring where R is a PID.

12 votes

Happy $\pi$-day! Is it true that $\sum_{p \;\text{prime} } \frac{1}{{\pi}^p} < \pi -\lfloor \pi \rfloor$?

12 votes
Accepted

Number of paths on $\mathbb Z^d$

11 votes

Is it possible to split the natural numbers into a finite number of sets so that no pair of numbers within a set adds up to a square?

11 votes
Accepted

Interesting behavior of the $2$-tag system $\{a\rightarrow abc,b\rightarrow ab,c\rightarrow c\}$

10 votes

Zero divisor or unit

10 votes

Evaluate the following integral $ \int_1^{\infty} \frac{\lbrace x\rbrace-\frac{1}2}{x} dx$

9 votes

meaning of topology on a finite set

8 votes
Accepted

Number of points of an elliptic curve

8 votes
Accepted

Heron's Formula

8 votes

Find positive integer $x$ where $x^{13} = 21982145917308330487013369$

8 votes
Accepted

General way to determine $\mathbb{Q}(\gamma) = \mathbb{Q}(\alpha,\beta)$ given $\alpha$ and $\beta$

8 votes

Localization commutes with arbitrary direct sums

8 votes

Prove that $x^3+2y^3+4z^3\equiv6xyz \pmod{7} \Rightarrow x\equiv y\equiv z\equiv 0 \pmod{7}$

8 votes
Accepted

A bound of the harmonic series of squares.

7 votes

How do you evaluate $\int_{0}^{1} \frac{(3x^3-x^2+2x-4)}{\sqrt{x^2-3x+2}} \, dx$?

7 votes
Accepted

–°haracteristic property of polynomials with integer coefficients

7 votes
Accepted

$f:\mathbb Q\to\mathbb C$ satisfying $f(x_1+\dots+x_{1988})=f(x_1)\dots f(x_{1988})$ and $\overline{f(1988)}f(x)=f(1988)\overline{f(x)}$

7 votes

Proving $\sin\left(\frac{2\pi}{p}\right)$ is irrational where $p\geqslant3$ is prime

7 votes
Accepted

prime counting function $\pi(x)$ is $o(x)$

7 votes
Accepted

Diffeomorphisms of the torus $\mathbb T^n$

7 votes
Accepted

subgroup of $\Bbb Q_p^×$ of index p contains $(\Bbb Q_p^×)^p$ as subgroup

6 votes
Accepted

Bijective Mapping Between $\mathbb{R}$ and $\mathbb{R}\setminus\{0\}$

6 votes
Accepted

Functional equation $f(x)f(f(x))=1$

6 votes

How am I getting i = -i from the quaternion formula?

6 votes

Prove that $|A+A|=2n-1$ if and only if the sequence $A$ is an AP.

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