[/quote]
,
vertices, each edge has one of the colors 
,
,
.
,
groups such that any two vertices connected by an edge of color 
are in different groups, find the minimum possible value of 
.
such that, for all 
,
such that for all integer 
and a subset 
of ![$[n],$](http://latex.artofproblemsolving.com/d/2/7/d27d2715f4f95c24a28b7c6371a006d4c803b2cf.png)
satisfy 
for all 
then 
be the set of positive integers. Find all functions 
such that for all 
,![\[m^2f(m) + n^2f(n) + 3mn(m + n)\]](http://latex.artofproblemsolving.com/0/f/f/0ff783fa217b7be4bda5006e417f1471ea3a6fca.png)
is a perfect cube.
and 
.
![$\mathbb{R}[x]$](http://latex.artofproblemsolving.com/a/8/8/a88b9f4858016b1771635c611d44b56161a08009.png)
be the set of all polynomials with real coefficients. Find all functions ![$f: \mathbb{R}[x] \rightarrow \mathbb{R}[x]$](http://latex.artofproblemsolving.com/0/3/3/033be3ab043bd47e537f01791c813739ad5c7da5.png)
satisfying the following conditions:
maps the zero polynomial to itself,![$P \in \mathbb{R}[x]$](http://latex.artofproblemsolving.com/f/7/c/f7c4c970908aa5570a9afcc45fc16c1d36cc3d5d.png)
,
,![$P, Q \in \mathbb{R}[x]$](http://latex.artofproblemsolving.com/c/3/0/c301578bade5b93056d77454921cba0a9812212c.png)
,
and 
have the same set of real roots.
be a square of center 
and let 
be the symmetric of the point 
with respect to point 
.
be the intersection of 
and 
,
and 
.
is the angle bisector of 
.
be reals such that 
Show that
Let 
and 
Prove that
be a polygon formed by the edges of an infinite chessboard, which does not intersect itself. Let the numbers 
represent the number of unit squares that have exactly 
edges on the boundary of 
such that the inequality 
holds for each polygon constructed with these conditions.
and 
Find the value range of 
and 
with real coefficients satisfying
Y by mahanmath, Adventure10, Mango247
We have connected four metal pieces to each other such that they have formed a tetragon in space and also the angle between two connected metal pieces can vary.
In the case that the tetragon can't be put in the plane, we've marked a point on each of the pieces such that they are all on a plane. Prove that as the tetragon varies, that four points remain on a plane.
proposed by Erfan Salavati
In the case that the tetragon can't be put in the plane, we've marked a point on each of the pieces such that they are all on a plane. Prove that as the tetragon varies, that four points remain on a plane.
proposed by Erfan Salavati
This post has been edited 1 time. Last edited by goodar2006, Sep 13, 2011, 6:54 PM
= Equal Ratios In Quaqdrilateral 
.
Call points 
on 
respectively special if they are coplanar for some arbitrary orientation of the tetragon so that it's not on one plane. Let 
be the signed distances of 
to the plane. We have
lie on 
so that 
are coplanar, and define 
as the distances from 
,
Hence we've shown that 
