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For positive integers \( a, b, c \), find all possible positive integer values o
Jackson0423   11
N 3 hours ago by zoinkers
For positive integers \( a, b, c \), find all possible positive integer values of
\[
\frac{a}{b} + \frac{b}{c} + \frac{c}{a}.
\]
11 replies
Jackson0423
Apr 13, 2025
zoinkers
3 hours ago
Set summed with itself
Math-Problem-Solving   1
N 4 hours ago by pi_quadrat_sechstel
Source: Awesomemath Sample Problems
Let $A = \{1, 4, \ldots, n^2\}$ be the set of the first $n$ perfect squares of nonzero integers. Suppose that $A \subset B + B$ for some $B \subset \mathbb{Z}$. Here $B + B$ stands for the set $\{b_1 + b_2 : b_1, b_2 \in B\}$. Prove that $|B| \geq |A|^{2/3 - \epsilon}$ holds for every $\epsilon > 0$.
1 reply
+1 w
Math-Problem-Solving
Today at 1:59 AM
pi_quadrat_sechstel
4 hours ago
(x+y) f(2yf(x)+f(y))=x^3 f(yf(x)) for all x,y\in R^+
parmenides51   12
N 4 hours ago by MuradSafarli
Source: Balkan BMO Shortlist 2015 A4
Find all functions $f: \mathbb{R}^{+} \rightarrow \mathbb{R}^{+}$ such that $$
(x+y)f(2yf(x)+f(y))=x^{3}f(yf(x)),  \ \ \ \forall x,y\in \mathbb{R}^{+}.$$
(Albania)
12 replies
parmenides51
Aug 5, 2019
MuradSafarli
4 hours ago
Advanced topics in Inequalities
va2010   9
N 4 hours ago by Strangett
So a while ago, I compiled some tricks on inequalities. You are welcome to post solutions below!
9 replies
va2010
Mar 7, 2015
Strangett
4 hours ago
24 Aug FE problem
nicky-glass   3
N 4 hours ago by pco
Source: Baltic Way 1995
$f:\mathbb R\setminus \{0\} \to \mathbb R$
(i) $f(1)=1$,
(ii) $\forall x,y,x+y \neq 0:f(\frac{1}{x+y})=f(\frac{1}{x})+f(\frac{1}{y}) : P(x,y)$
(iii) $\forall x,y,x+y \neq 0:(x+y)f(x+y)=xyf(x)f(y) :Q(x,y)$
$f=?$
3 replies
nicky-glass
Aug 24, 2016
pco
4 hours ago
Simply equation but hard
giangtruong13   1
N 4 hours ago by anduran
Find all integer pairs $(x,y)$ satisfy that: $$(x^2+y)(y^2+x)=(x-y)^3$$
1 reply
giangtruong13
6 hours ago
anduran
4 hours ago
Hard Polynomial Problem
MinhDucDangCHL2000   1
N 5 hours ago by Tung-CHL
Source: IDK
Let $P(x)$ be a polynomial with integer coefficients. Suppose there exist infinitely many integer pairs $(a,b)$ such that $P(a) + P(b) = 0$. Prove that the graph of $P(x)$ is symmetric about a point (i.e., it has a center of symmetry).
1 reply
MinhDucDangCHL2000
Today at 2:44 PM
Tung-CHL
5 hours ago
IMO LongList 1985 CYP2 - System of Simultaneous Equations
Amir Hossein   13
N 5 hours ago by cubres
Solve the system of simultaneous equations
\[\sqrt x - \frac 1y - 2w + 3z = 1,\]\[x + \frac{1}{y^2} - 4w^2 - 9z^2 = 3,\]\[x \sqrt x - \frac{1}{y^3} - 8w^3 + 27z^3 = -5,\]\[x^2 + \frac{1}{y^4} - 16w^4 - 81z^4 = 15.\]
13 replies
Amir Hossein
Sep 10, 2010
cubres
5 hours ago
Centroid Distance Identity in Triangle
zeta1   5
N 5 hours ago by DottedCaculator
Let M be any point inside triangle ABC, and let G be the centroid of triangle ABC. Prove that:

\[
|MA|^2 + |MB|^2 + |MC|^2 = |GA|^2 + |GB|^2 + |GC|^2 + 3|MG|^2
\]
5 replies
zeta1
Today at 12:28 PM
DottedCaculator
5 hours ago
Numbers not power of 5
Kayak   34
N 5 hours ago by cursed_tangent1434
Source: Indian TST D1 P2
Show that there do not exist natural numbers $a_1, a_2, \dots, a_{2018}$ such that the numbers \[ (a_1)^{2018}+a_2, (a_2)^{2018}+a_3, \dots, (a_{2018})^{2018}+a_1 \]are all powers of $5$

Proposed by Tejaswi Navilarekallu
34 replies
Kayak
Jul 17, 2019
cursed_tangent1434
5 hours ago
a