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PNT
  • Member for 3 years, 1 month
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14 votes
5 answers
552 views

Set of primes dividing $2^n+3^n$.

13 votes
5 answers
389 views

Prove that $\frac{a^2}{a^2+bc}+\frac{b^2}{b^2+ac}+\frac{c^2}{c^2+ab}<2$

10 votes
3 answers
503 views

Why ignoring the function $f(x)=1/(1+x^2)$?

10 votes
5 answers
952 views

Prove that $\sum_{1\le i<j\le n}\frac{x_ix_j}{(1-x_i)(1-x_j)} \le \frac{n(n-1)}{2(2n-1)^2}$

8 votes
4 answers
3k views

U-sub without changing the bounds of integration

7 votes
2 answers
278 views

There are no positive integers such that $a+b^2$, $a^2+b$ are both powers of $5$

6 votes
1 answer
204 views

When is $2^2+...+n^2=p^k$.

6 votes
3 answers
1k views

Taylor series for $\sqrt[3]{x+1}$

5 votes
7 answers
387 views

Prove that $\angle AEF =90^\circ$ given a square $ABCD$

5 votes
1 answer
179 views

the curvature as a function of $t$

5 votes
1 answer
403 views

Surjectivity of $a^x+x\pmod n$.

5 votes
1 answer
534 views

Dividing bars of chocolate.

5 votes
2 answers
147 views

Given $x^4+y^4+z^4=1$ Find the minimum value of $\sum_{cyc}\frac{x^3}{1-x^8}$.

5 votes
3 answers
166 views

$\forall a\ge 2, \exists n\ge 1$ such that $2n+1\mid a+n!$

4 votes
4 answers
222 views

On swapping the order of a summation

4 votes
2 answers
141 views

Confusions in Holder's Inequality

4 votes
1 answer
459 views

Where is my error in this incorrect proof of Wolstenholme's theorem?

4 votes
1 answer
159 views

Prime divisors of $a^n+b$.

4 votes
1 answer
383 views

Prove that there exist infinitely many values of $n$ such that $z_n, z_{n+1}, …, z_{n+2019}$ are all odd.

4 votes
1 answer
150 views

Constructing "Double" circumscribed pentagons.

4 votes
2 answers
110 views

Find all $(p,n)$ s.t. $p+n\mid pn $

3 votes
1 answer
424 views

Does $f(x+1)-f(x)$ constant imply $f$ is linear?

3 votes
2 answers
799 views

If $x+y+z \geq xyz$ Prove that $x^2 + y^2 + z^2 \geq xyz$.

3 votes
1 answer
199 views

Find all sets $A$ that satisfy condition $a+b \in A \implies ab\in A$.

3 votes
6 answers
166 views

Prove that $\frac{a^{2}+1}{b}+\frac{b^{2}+1}{a} \geq 4$

3 votes
1 answer
46 views

Can you prove that if $\mid D_n \mid = m$, where $m$ is odd, then $n$ is a perfect square. [duplicate]

3 votes
4 answers
139 views

$x^3 + y^3 +3x^2 y^2 =x^3y^3$ Find all possible values to $\frac{x+y}{xy}$

3 votes
3 answers
126 views

$x,y\in \mathbb Z^+$ Show that $P(x)=P(y) \implies x=y$

3 votes
5 answers
196 views

Can you solve $\int 1/(x^2+1)^2\, dx$ [duplicate]

3 votes
1 answer
106 views

Find the largest $n$ such that $\sqrt{n+60}+\sqrt{n}=\sqrt{m}$, for $\sqrt{m} \notin \mathbb N$

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