Find all p(x) such that p(p) is a power of 2

by truongphatt2668, May 15, 2025, 1:05 PM

Find all polynomial $P(x) \in \mathbb{R}[x]$ such that:
$$P(p_i) = 2^{a_i}$$with $p_i$ is an $i$ th prime and $a_i$ is an arbitrary positive integer.

Nice original fe

by Rayanelba, May 15, 2025, 12:37 PM

Find all functions $f: \mathbb{R}_{>0} \to \mathbb{R}_{>0}$ that verify the following equation :
$P(x,y):f(x+yf(x))+f(f(x))=f(xy)+2x$
This post has been edited 2 times. Last edited by Rayanelba, an hour ago
Reason: .

Angle Relationships in Triangles

by steven_zhang123, May 14, 2025, 11:09 PM

In $\triangle ABC$, $AB > AC$. The internal angle bisector of $\angle BAC$ and the external angle bisector of $\angle BAC$ intersect the ray $BC$ at points $D$ and $E$, respectively. Given that $CE - CD = 2AC$, prove that $\angle ACB = 2\angle ABC$.

Points on the sides of cyclic quadrilateral satisfy the angle conditions

by AlperenINAN, May 11, 2025, 7:15 PM

Let $ABCD$ be a cyclic quadrilateral and let the intersection point of lines $AB$ and $CD$ be $E$. Let the points $K$ and $L$ be arbitrary points on sides $CD$ and $AB$ respectively, which satisfy the conditions
$$\angle KAD = \angle KBC \quad \text{and} \quad \angle LDA = \angle LCB.$$Prove that $EK = EL$.
This post has been edited 2 times. Last edited by AlperenINAN, May 11, 2025, 7:59 PM

Sixth smallest divisor

by sevket12, Feb 8, 2025, 12:39 PM

Find all positive integers $n$ such that the number
\[
\frac{3 + \sqrt{4n + 9}}{2}
\]is the sixth smallest positive divisor of $n$.

functional equation

by uaua, Jan 3, 2023, 2:52 AM

f:R--R
f(f(x)+xy) = xf(x) + f(x)

APMO 2017: (ADZ) passes through M

by BartSimpsons, May 14, 2017, 3:20 PM

Let $ABC$ be a triangle with $AB < AC$. Let $D$ be the intersection point of the internal bisector of angle $BAC$ and the circumcircle of $ABC$. Let $Z$ be the intersection point of the perpendicular bisector of $AC$ with the external bisector of angle $\angle{BAC}$. Prove that the midpoint of the segment $AB$ lies on the circumcircle of triangle $ADZ$.

Olimpiada de Matemáticas, Nicaragua
This post has been edited 1 time. Last edited by MellowMelon, May 17, 2017, 5:50 PM
Reason: add proposer

Israeli Mathematical Olympiad 1995

by YanYau, Apr 8, 2016, 9:16 AM

Let $PQ$ be the diameter of semicircle $H$. Circle $O$ is internally tangent to $H$ and tangent to $PQ$ at $C$. Let $A$ be a point on $H$ and $B$ a point on $PQ$ such that $AB\perp PQ$ and is tangent to $O$. Prove that $AC$ bisects $\angle PAB$

ARO 2011 11-8

by sartt, May 3, 2011, 11:23 AM

Let $N$ be the midpoint of arc $ABC$ of the circumcircle of triangle $ABC$, let $M$ be the midpoint of $AC$ and let $I_1, I_2$ be the incentres of triangles $ABM$ and $CBM$. Prove that points $I_1, I_2, B, N$ lie on a circle.

M. Kungojin
This post has been edited 3 times. Last edited by sartt, May 6, 2011, 11:10 AM

IMO 2010 Problem 1

by canada, Jul 7, 2010, 4:32 PM

Find all function $f:\mathbb{R}\rightarrow\mathbb{R}$ such that for all $x,y\in\mathbb{R}$ the following equality holds \[
f(\left\lfloor x\right\rfloor y)=f(x)\left\lfloor f(y)\right\rfloor \] where $\left\lfloor a\right\rfloor $ is greatest integer not greater than $a.$

Proposed by Pierre Bornsztein, France
This post has been edited 1 time. Last edited by djmathman, Apr 27, 2015, 2:58 PM
Reason: formatting

Stay insane,Coz it's your will, labour and pain,which takes you to the top of the mountain.

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  • First post of 2024

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  • Nice blog ! Your isogonality lemma is really powerful !

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  • Thanks for the nice blog.

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  • I think this might be silly but ... when should we expect to have another post ?? I am very keen to see it :D

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  • Let's all echo what's written in the blog description - Stay Insane / 'Cause it's your labor, will and pain/ That takes you to the top of soda fountain :D

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  • hey utkarsh jee is over now ... continue your elementary blog pleaseeeeeee!

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  • INTERSTING BLOG

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  • I have no plans for this blog right now....
    No time here people !
    But lets see....
    I may try some combinatorics :P

    by utkarshgupta, Feb 15, 2017, 12:47 PM

  • Thanks for the nice blog!

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  • Revive it!!!
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